Archive for the ‘Theory’ Category

Rotoworld’s Pitcher Values

8 Comments
February 23rd, 2009 by Mays
Categories: Theory

You may have noticed a recurring theme here is dealing with valuing pitchers relative to hitters. Average draft position starts drafting pitchers in round 2 and doesn’t really get going on them until the fourth round. The Price Guide (as well as several other sources) tends to rank the top-tier pitching higher and advocates grabbing Santana in the first round.

(Since it’s a topic I seem to be stuck on, I have appreciated the comments that have been left on the various pitcher/hitter ADP posts. Lots of stuff has been written that has really made me think about this.)

Anyways, being ever vigilant for evidence that supports one approach or the other, I took a look at how Rotoworld valued pitchers. Here are a few SP dollar values from their magazine, with overall rankings included:

5. Johan Santana – $37 (tied with Pujols)
14. Tim Lincecum – $31
19. Roy Halladay – $30
22. Cole Hamels – $29
26. Brandon Webb – $28
29. CC Sabathia – $28

Not quite as aggressive as the Price Guide, but considerably higher than ADP. Actually, those are probably a good indication of what you would end up paying if you were following the Price Guide and the rest of your league was using ADP.

SGPs Part IV: The Difficulty of Inconsistent Scales

3 Comments
February 20th, 2009 by Mays
Categories: Theory

I have mentioned that I think Standings Gain Points (SGPs) are a pretty good method of determining player values for fantasy. However, I don’t use them for the Price Guide based on some shortcomings I have found. This week I’m pointing out some of the quibbles that I have with the SGP methodology:

If you have looked at any of the projection systems that the Price Guide uses, you may have noticed that they look a little conservative. Marcel projects Ryan Howard to lead the league with 119 RBI? No pitcher is expected to finish with more than 16 wins?

These things are not indicative of problems with the projection systems and are, in fact, positive features. While it’s very likely that someone will get close to 20 wins, it is impossible to predict who it will be. I’d bet that someone tops 130 RBI, but I don’t have a clue who it will be. When you are predicting something as unpredictable as baseball stats, the smart route is to be conservative. (Tango explains this fully here.)

So it’s clear that our projections are operating on a different scale than the real life stats. On the projections scale, a player projected for 100 RBIs is elite. In real life, he’s just “pretty good.”

What happens when you mix-and-match the projected scale with the real life scale? Standings Gain Points attempts to find out. On one hand, it’s looking at the stats from last year (the “real life scale”) to determine the relative value of each category. It then takes those values and applies them to a completely different scale — the regressed scale from the projections.

Consider saves, a highly variable stat: Players on fantasy teams will always finish with more saves than what was projected for players before the year. When SGPs look at last year’s stats, they might see about six saves separating each team (McGee came up with 6.2 – 6.3 in his book) and determine that 6 saves are worth 1 SGP.

Remember, however, that the projections don’t project that many saves! And on a scale with fewer saves, the saves that are available become more valuable.

This is a nuance that is missed by SGP, but is caught by the Price Guide. Notice that when the Price Guide determines the value of each save, it is using the scale determined by the projections themselves. Which means it is willing to value saves from the reliable closers more highly than SGP does.

SGPs Part III: The Problem of League Specifics

6 Comments
February 19th, 2009 by Mays
Categories: Theory

I have mentioned that I think Standings Gain Points (SGPs) are a pretty good method of determining player values for fantasy. However, I don’t use them for the Price Guide based on some shortcomings I have found. This week I’m pointing out some of the quibbles that I have with the SGP methodology:

How many types of fantasy baseball leagues are there out there? Fantasy leagues might have 6 teams or 30 teams or anything in between. They use different stats: 4×4 and 5×5 and 6×6 and hundreds of other combinations. Different leagues start different positions: two catchers, middle infield, middle relievers, etc.

When I was developing the Price Guide to build fantasy values, I obviously wanted something that could be used by people outside of the Standard League. And requiring that flexibility ruled out using Standings Gain Points.

See, SGPs are tied to the final standings of a specific league. They are built based on a certain number of owners, a certain number of hitters, and a certain number of pitchers. The more you deviate from those specific settings, the less accurate SGP prices will be.

Consider Razzball’s Point Shares, which are essentially a SGP system. A while back I drafted a league that had 6 teams using Point Shares and 6 teams using the Price Guide, tailored specifically to the league settings that Point Shares were based on. When I checked the final results, the Price Guide teams and the Point Shares teams split the points right down the middle. Out of 550 total points, each system got 275 — exactly half. In a league customized for a SGP system, SGPs and the Price Guide can do equally well.

However, if you change any single aspect of that league, the Price Guide will very likely take the top six spots. If you add a couple of new positions or add a couple of teams, the Price Guide values will adjust for it, and SGPs won’t. (This fact became very clear when I setup the Price Guide/Point Shares league, which wasn’t even competitive when I accidentally left out CI and MI.)

I imagine most people can live with SGPs inflexibility: After all, most people aren’t trying to build an online tool that works for any league, they just want a system that works for their league.

But what happens if your league decides to expand from 10 to 12 teams this year? What if they decide to use OBP instead of AVG?

If anything in your league changes from the year before, the accuracy of your SGPs is greatly compromised; but the Price Guide will adjust for whatever settings your league chooses.

SGPs Part II: The Danger of Past Results

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February 18th, 2009 by Mays
Categories: Theory

I have mentioned that I think Standings Gain Points (SGPs) are a pretty good method of determining player values for fantasy. However, I don’t use them for the Price Guide based on some shortcomings I have found. This week I’m pointing out some of the quibbles that I have with the SGP methodology:

There’s a standard disclaimer in financial investments that “past results do not guarantee future returns.” Just because a stock has done well in the past, it doesn’t mean that it will continue to do well. It’s a principle that applies to baseball as well: A good hitter who is 0/10 against a pitcher might go four-for-four the next time they meet. And I think a big problem with SGP is expecting the next year to be just like the past one.

Since SGPs are based on the standings from previous years, they will be affected by past strategies. If two owners decided to punt saves last year, SGP will factor their save totals into this year’s denominators. If a few teams ran away with stolen bases, that will be included in the prices as well.

But remember, past results do not guarantee future returns. What happens if no one punts saves this year? What happens if stolen bases end up being a tight race, with no one pulling away with a huge lead?

Fantasy owners are dynamic: They are trying out new strategies from year to year. They are zigging if they saw people zag last year. You can’t rely on the same strategies being used from year to year, but that is exactly the assumption that SGP makes.

In his book, Art McGee does make some efforts to account for this problem. He suggests throwing out the top and bottom teams when building your SGP denominators, because these are more likely to be outliers. He recommends using multiple years of data if you have it.

Definitely, the more data you have to work with, the better your SGPs will be. But when I developed the Price Guide, I wanted a method that didn’t require years of historical, league-specific data to be effective.

And speaking of league-specifics, that’s actually my next quibble with the SGP method.

Standings Gain Points, Part I (Introduction)

12 Comments
February 17th, 2009 by Mays
Categories: Theory

Since the start of fantasy baseball, the constant challenge that participants have faced is trying to determine players’ values. What do you pay for a guy who can get you 30 SB? Is he worth more or less than someone who hits 30 HR? Would you trade him for someone with a 3.65 ERA?

Really, it’s a problem that boils down to this: How do you measuring a player’s contribution, when the contributions are based on 8 or 10 different scales (i.e. the 4×4 or 5×5 stat categories)? The solution is to convert all of the categories to use a common scale.

One way to do this is to use Standings Gain Points. Standings Gain Points are a system developed by Alex Patton and popularized by the recent re-release of Art McGee’s How To Value Players For Rotisserie Baseball. Derek Carty praises SGP as “the greatest, most logical way of valuing players I’ve ever heard of.”

How do SGPs work?
The basic idea behind SGP is to look at the final standings from your league in previous years and determine how much of each stat it takes to pick up an extra point in the standings. How many homeruns would it take to move up one spot in the homerun standings? How many strikeouts separate each team?

If you notice that there are 10 HR separating each team, then you know that, on average, it will take an additional 10 HR to move up one point in the standings. So 10 HR are equal to 1 SGP. Do the same thing for all of the other stats, and all of a sudden you have reduced a player’s contributions from across four or five categories down to one, simple number. Sort players by that magic number and you will have rankings customized for your draft. Convert that number into a dollar value and you are ready for an auction.

To be honest, I think Standings Gain Points is overall a pretty sound methodology. However, I do think it has some flaws that keep it from being “the greatest, most logical way of valuing players” ever.

This week I’ll be taking a look at some of the problems I see with SGP, and also explain why I decided to take a different approach when building my own valuation system, the Price Guide.

More Pitchers in the First Round

11 Comments
February 16th, 2009 by Mays
Categories: Theory

Another advocate of drafting pitchers in the first round: Baseball Prospectus’s Player Forecast Manager. Here’s an excerpt from an article I came across:

Q: It looks like the overvaluation of pitchers is back again. After the first day, the valuations were normal, but the PFM is currently showing pitchers as the second, third, fourth, and 6th-8th most valuable players in the game for fantasy purposes.

BP’s Ben Murphy explains that, although it might look like a bug, the high pitcher values are correct based on their methodology.

So why does everyone who runs the numbers come to the conclusion that the top-tier starters are worth taking in the first round? Is everyone overlooking the unpredictability factor?

Playing with Marcel’s Reliability Ratings

3 Comments
February 10th, 2009 by Mays
Categories: Theory

In last week’s discussions on why the Price Guide’s values differ from what you see in average draft position (ADP), Nick made the following comment:

Regarding risk and projections, I know that Marcel contains reliability scores and PECOTA has a beta score, but I’m not sure exactly how they are incorporated into the projection numbers themselves.

He references a comment from Tango on Razzball:

I would say that you MUST use the “reliability” column provided with Marcels. And, the playing time forecast is the most important thing in fantasy sports, so you have to get that right first.

If you are familiar with the Marcel projections, you may have noticed that each player’s stats have a reliability rating. This doesn’t indicate injury chances or anything like that, but measures the confidence level of the projection. Since the Marcel’s are based on a player’s performance from the past three years, a player who has been in the majors since 2006 will be projected with a higher reliability than, say, Evan Longoria.

So what happens if we adjust our Price Guide values using Marcel’s reliability factor? Will that fix the discrepancy we see in pitcher values?

Here’s an illustration of what changes with the Price Guide’s fantasy dollar values for pitchers when reliability is considered:

Pitcher Values, With and Without Reliability Scores

Notice what happens when the reliability ratings were added: The values for the top nine pitchers were practically unchanged, because these are the pitchers that have shown themselves to be consistent performers over the past few years (Santana, Sabathia, Webb, Haren, etc.). After those nine, the prices for the rest of the pitchers dropped by about $3-4 each, all the way down to the bottom. Those are the players that have not put up consistent numbers over a large number of innings.

It’s not a drastic change, but it does fit a little bit better with what we see happening in average drafts.

You may remember from a previous post that three of the ten players that the Price Guide diverged from ADP most widely on were RP. Here’s how the draft rankings on those three look with reliability factored in:

Player Without Reliability With Reliability ADP
Jonathan Papelbon 31st 53rd 54.1
Joe Nathan 41st 63rd 72.93
Francisco Rodriguez 51st 72nd 72.05

Wow! Considering reliability, we practically eliminated a gap of about 20 spots. Papelbon and K-Rod are both eerily close to what ADP suggests now. The change in reliever rankings is easily the biggest effect we see after adding reliability.

I’m hoping to have an option added within the next day or two to use reliability factors when building fantasy values on the Price Guide (at least for Marcel, which are the only projections that include a reliability ranking). Reliability doesn’t make a huge difference, but I think it does help a little. The top talent is pushed up while the lower tiers are flattened out a bit. Due to low IP totals, relievers are discounted especially.

We still haven’t explained all of the SP in the first round. Even after we account for reliability, the Price Guide still thinks top-tier pitchers are worth paying for. But I think this gets us a step closer to the most accurate values.

More Thoughts on ADP

9 Comments
February 4th, 2009 by Mays
Categories: Price Guide, Theory

Let’s continue developing some of the ideas from yesterday… When we looked at things yesterday, we noticed that the Price Guide tends to rank the top-tier pitchers higher than they typically are ranked by fantasy average draft position (ADP). Why is that?

I see the following explanations as possible:

Explanation #1: The Price Guide is wrong.
Now that’s the sort of talk that gets me defensive. I’m pretty confident that the Price Guide’s fantasy values are the most accurate around. But I hope that I would still be able to admit if there were flaws in some area.

I do see a couple of problems with this explanation:

  • The Price Guide’s rankings are in line with what other fantasy player valuations systems (such as Razzball’s Point Shares) suggest. With each system using their methodology, it doesn’t seem likely that they independently all came to the wrong conclusion.
  • The Price Guide’s rankings fit my own experience in auctions. In fantasy leagues that I’ve been in, the top hitters might go for around $45, and there are usually a couple of pitchers around $40 as well. The difference appears to only show up in a straight draft, which leads me to my second theory…

Explanation #2: The drafters are wrong.
There’s no doubt that acting in large groups will not necessarily increase the intelligence of the population. Large groups of ignorant people can still be just as ignorant (e.g. mobs, Yankee fans).

However, I am impressed at how accurate and efficient the fantasy “market” can be. When I looked at the 70/30 split, it turned out that fantasy players nailed the percentages without even knowing the reasons behind it. I’m willing to give the wisdom of the crowds some benefit of the doubt here as well, although I think drafter error is probably playing some role in the discrepancy.

So what does that leave?

Explanation #3: Drafts require different rankings than auctions.
If we accept the Price Guide’s dollar values as accurate, and also accept that ADP as at least somewhat accurate, what options are left?

The idea I’m toying with is that maybe drafts require a different set of rankings than auctions. It’s an idea that I’m not convinced of, because it seems like values should be the same no matter what method is used for picking players.

However, with an auction, I can get a $45 hitter and a $45 pitcher if I so desire. But with a draft, I can only get one or the other. Should that make a difference? I honestly don’t see why it would, but it’s the only factor left that I can think of.

What do you think?

Diverging from ADP

8 Comments
February 3rd, 2009 by Mays
Categories: Price Guide, Theory

Let’s take a look at the players with the largest difference in ADP compared to the rankings given by the Price Guide.

I took the Yahoo League ADP rankings from Mock Draft Central and compared them to the rankings from the Price Guide, using the Marcel projections for a Yahoo league. Here are the 15 players that biggest gap between the Price Guide and ADP rankings:

  1. Dan Haren
  2. Roy Halladay
  3. Magglio Ordonez
  4. Joe Mauer
  5. CC Sabathia
  6. Joe Nathan
  7. Cole Hamels
  8. Brandon Webb
  9. Jake Peavy
  10. Bobby Abreu
  11. Chipper Jones
  12. Brian McCann
  13. Russell Martin
  14. Jonathan Papelbon
  15. Francisco Rodriguez

Notice a trend there? 9 P, 3 C, and 3 others.

First off, I’m not sure what drafters don’t like about Ordonez, Abreu, and Jones. Maybe they expect Abreu to continue to decline, maybe they expect Chipper to get hurt. I’m not sure exactly, but those players make up the minority of the difference.

The catchers are a slightly bigger group. I continue to maintain that people undervalue the top-tier catchers. I think that they get tied up on the absolute stats and forget that what really matters are the stats relative to the replacement level. Factor in the baseline, and a catcher who can hit 20 HR is worth more than a lot of guys who can hit 35. (And this is a one-catcher Yahoo-style league.)

I’ll keep preaching that and keep taking catchers in the 2nd-3rd rounds until someone can convince me otherwise.

And then we have the most significant discrepancy: Pitchers. For a Yahoo league, the Price Guide puts CC Sabathia and Johan Santana as the top two overall draft choices. Clearly that doesn’t square with the ADPs, which don’t have any pitchers in the top 16.

However, the Price Guide isn’t alone in its love for pitchers: Razzball’s Player Rater puts 4-5 pitchers in the first round, including SP at #2 and #4.

And in my experience with auctions, it doesn’t seem unusual for the top pitchers to be equivalent to the top hitters. (Note that the Price Guide’s hitting/pitching split lines up with what you expect for auctions.)

I don’t think this is Price Guide vs. ADP; I think it’s auction strategy vs. draft strategy.

Which still leaves the questions: Why don’t drafters go after the top pitchers?

Why People Pay More For Top Players

3 Comments
February 2nd, 2009 by Mays
Categories: Price Guide, Theory

Brilliant observation, huh? People pay more money for good players than bad ones. How long did it take me to realize that? Actually, that’s not what I’m talking about here.

It’s clear that people pay more for top-tier players than for lesser players. However, it’s not immediately obvious why the Price Guide tends to understate what people tend to pay for the top-tier players. Why do people spend more for top players than what the Price Guide recommends?

As quick as I am to defend the Price Guide’s methodology, this is one case where I think people’s behavior might be more accurate. I don’t think my methodology is flawed, I just think it’s leaving out a couple of factors that come in to play in a draft:

Sleeper Mentality
Fantasy players tend to pay less for low-end “consistency picks,” and instead target late-round high-risk/reward sleepers. By targeting sleepers late, they are able to spend more money early.

So instead of spending $6 on a veteran platoon-OF or a journeyman SP, most teams will go after a rookie player valued at -$2, knowing that he has the potential to beat that projection. If he doesn’t, that’s OK, because there’s no problem with dropping him when someone better comes along during the season.

Divergent Opinions
Fantasy players tend to have more divergent opinions about late round players, which means these players go cheaper. Guys that the Price Guide projects for $6 will often go for $2-3, because there will be some owners who have them ranked below replacement level.

The top-tier guys are more predictable–everyone has a very similar ranking for the top ten players. Owners will take their savings from the late-round players and spend the money at the top instead.

Open Positions
Related to that, owners may be willing to spend money on late-round guys, but can’t because they have already filled a certain position. Compare that to the first few bids, when every team has money and open positions. The opening bids are also where the top-tier players are usually brought up.

Add all of those factors up, and I think it enough to maybe skew the values to give an extra 10-15% to the top players. And while that may work as a rule of thumb, I’d really like to be able to quantify some of these factors into the Price Guide.