Baseball Prospectus releases PECOTA projections for 2015 season

From Mike Gianella and SABR member Rob McQuown at Baseball Prospectus on January 29, 2015:

Welcome to PECOTA day, sponsored by DraftKings. Premium subscribers can now download the 2015 Weighted Means Spreadsheet under the Fantasy tab at the top of this page, or by clicking “manage your profile.” Player pages have been updated with these projections, as have team depth charts (with projected standings) and the fantasy team tracker. Allow us to expand on a few details that might be helpful to you.

Why Does PECOTA Hate My Team?

Every year, fantasy owners and fans of teams ask this question, “Why Does PECOTA Hate My Team?” Last year, Deadspin compiled five dozen “(maybe) surprising player projections.” This season, there’s already been a Lineup Card with eight such surprising projections and Sam Miller did some Pebble Hunting to reveal some of the “winners” in the PECOTA pitching projections. This all raises the question of why Baseball Prospectus would keep publishing surprising projections. Shouldn’t these things be getting better with time, as the system is refined and there’s more data?

It would be disingenuous to suggest that projections never miss the mark. Sometimes by a lot. In fact, last season alone, 39 of the 362 position players for which Baseball Prospectus had projected 100 or more plate appearances actually amassed 100 or more plate appearances with very unexpected (to PECOTA) hitting performances. We looked at these players’ WARP-per-600 plate appearances, with FRAA removed (yes, FRAA is important, but it’s projected differently and is—sometimes—much more out of the player’s control than batting stats). Using this metric, 39 players missed by 3.0 or more WARP-per-600. It could almost have been called, “Craig’s List”, as Mr. Allen Craig was the no. 9 culprit with a WARP-per-600 difference of 4.6 … and as those who saw him play for Boston can attest, he was making a strong run to top this list. PECOTA had projected 1.8 WARP-sans-FRAA in 426 PA (March 22nd projections), and he ended up with -1.7 WARP-sans-FRAA in 505 PA. But Dan Uggla took the top honors, falling 5.7 WARP-per-600 short of projections. Steve Pearce was no. 3 and represented the top over-performer, bettering his WARP-per-600 projection by 5.4.

The above examples come from the most stable group of players—batters who were projected to play and who did play. Yet, some of the most surprising projections entering the 2014 season ended up being close to perfect. For example, people who saw A.J. Burnett pitch in 2013 thought PECOTA needed glasses, as it projected Burnett to have one of the 10 largest declines in 2014. It projected his ERA to be 4.24, which, considering the drop in leaguewide offense in 2014, would have been adjusted to 4.14. His FIP in 2014? 4.14. Projections for Bryce Harper and B.J. Upton, tabbed as “(maybe) surprising” in the Deadspin article, proved prescient.. Remember the reaction when Chris Davis had a .289 TAv projection (again March 22)? That number ended up being optimistic (he posted a .271), even though when he was coming off a .358 TAv season virtually everyone thought PECOTA hated the guy.

Seriously, though, PECOTA doesn’t hate any player or anyone’s team. There are no biases in it based on anything but historical track records. For completeness, it should be noted that results such as the examples herein are not just “shrugged off” – both accurate and inaccurate results are processed. So, while some projections are going to be surprising, it’s important to keep in mind that all-in-all, the results have been very accurate over the years (thank you, Nate Silver!).

Read the full article here:

Originally published: January 29, 2015. Last Updated: January 29, 2015.