In a perfect world, player valuation would be simple - a player's stats would translate into the amount of dollars he earns, and you could price him accordingly. But even if you had the 2011 end-of-season stats in your possession, you would still make some errors in your draft or auction.

Let's say hypothetically you knew Roy Halladay would win 24 games, strike out 240 batters, and have an ERA of 2.10 and a WHIP of 0.95 in 240 IP. In a 12-team league, you'd be insane not to make him your first pick, and in an auction to bid $1 more than the most committed Halladay fanatic. Okay, so you take Halladay at No. 1, or you go to $39 in an NL-only league. He'll easily give you value if the only variable you consider is his stat line.

But let's say you take Halladay No. 1 overall, and the rest of your league likes to wait on pitching. And for whatever reason this year, that tendency is especially pronounced. Someone takes Felix Hernandez in Round 3, Tim Linecum in Round 4, Zack Greinke and Adam Wainright in Round 5, Jon Lester in Round 7, C.C. Sabathia and Cliff Lee in Round 9! Similarly in your auction, everyone's spending like crazy on hitting, and Greinke goes for $21, Wainwright for $19, Lee for $17.

In that case, Halladay - despite the incredible stats - is no longer as much of a bargain relative to the other pitchers. (You might still argue that it's worth it given your certainty and the ridiculous stats, but either way, it's less so relative to the rest of the pool in this example). Other people's behavior has impacted the quality of your Halladay purchase.

While this particular example is extreme and unrealistic, this kind of thing happens routinely in your drafts and auctions. You were agonizing over Matt Wieters or Geovany Soto in Round 8, settle on Wieters, and Soto goes in Round 14 after you've filled up at catcher. The rightness or wrongness of your decision to draft Wieters there isn't merely about how he'll do - it's also about what the rest of your league does in creating the market.

This complicates your draft a good deal because in addition to the uncertainty surrounding how your players will perform (as well as health, playing time, etc.), you're dealing with the uncertainty of what other people will do. Some might have a sound strategy, and others might be drafting blindly off an old magazine cheat sheet, but all will impact the quality of your picks.

Last year in the Yahoo! Friends and Family League, I had the sixth overall pick, and I was convinced in the innings cap format (where Ks are really K/9 since everyone winds up with the same number of IP), that Lincecum was the best value on the board. But I took Ryan Braun instead because I was afraid everyone would wait forever on pitching and cut into the value of my Lincecum pick. In the end, I think it was the right call, but I hated making it because it meant I was taking a player from whom I expected lesser stats-value. Of course, I got my "value" later in the draft with pitchers like Josh Beckett, and hitters like Justin Morneau and Jimmy Rollins got hurt, so it really didn't matter anyway.

But your league tendencies - insofar as they're predictable - are a key variable in player valuation.