Last Player Picked

You may have noticed that Baseball Prospectus is having a writing contest this summer, with the winner offered an extended writing gig with the company. The competition — Prospectus Idol — is styled after American Idol, complete with three judges and fan voting.

This week the contestants have written articles about fantasy baseball, and two of them have taken on the issue of fantasy player valuation: Brian Oakchunas submitted an article on a valuation system he calls VOFP — Value Over Fantasy Player. Tim Kniker’s article is for his Marginal Positional Value (MPV) methodology.

Now, there are plenty of fantasy valuation systems out there, including the Price Guide that you find on this site. In studying many of them, I’ve discovered that there are essentially three common aspects of all good systems:

1. Converting the stat categories (HR, SB, etc.) to a common scale.
2. Adjusting for position.
3. Adjusting for the baseline.

Numbers 2 and 3 are related, and it’s possible to combine them into one step. (The Price Guide, for example, only makes one adjustment for the positional replacement level.)

Also, #3 isn’t required for straight drafts, although it can help give a sense of scale for how good or bad a certain player is compared to the benchmark (either average player or replacement level player). A replacement level baseline is essential for auction leagues, where everyone is valued compared to a $1 player.

So how do the two Prospectus Idol systems look?

Here’s how Tim explains MPV:

MPV is calculated by determining how a given player, if inserted into the baseline roster, changes the team’s final statistics in each category. [...] The MPV column is simply the sum of the percent increases in each of the scoring columns, since in this league each category counts equally.

Basically, to value a player, you are adding his stats to an average fantasy team and subtracting from that team the stats of an average player at that position. That gives a percent change in each category between the new team and the average team, which Tim sums to get a player’s total value.

So the MPV system handles all three steps in valuation. My main issue would be his choice of baseline (players projected for 200+ AB), which seems geared towards his 20-team league. As commenters on the article mention, people would probably want to find a more appropriate baseline if their league varied much from that format.

Brian’s VOFP is based on the amount of each category it takes to move up one spot in the National Fantasy Baseball Championship rankings (#1 above). His baseline (#3) is 40th place in each category (out of 390 people), which he estimates is the average finish needed to win the championship.

He shrugs off making a positional adjustment (#2), and I think that is a mistake. His comments give me the impression that he understands the idea of positional scarcity, and he’s expecting the user to either do that work on their own or rely on their intuition.

Brian correctly notes that there is insight in the unadjusted number… That’s why I think the best thing to do is to list both numbers — before and after the positional adjustment. That’s what the Price Guide does and also what Tim advocates in his MPV article.

My overall thoughts on MPV and VOFP:

1. For their specific environments, the two systems presented in the Prospectus Idol contest look to be fairly good at estimating player value (although VOFP’s lack of a positional adjustment is, in my mind, a big negative for that approach).

2. Both MPV and VOFP are described in very league-specific terms and would need to be modified for any league variations.

3. Neither presented anything that I would consider to be an improvement over existing valuation methods.