I have already talked briefly about what Baseball Prospectus 2013 and PECOTA have to say about the Washington Nationals, but since PECOTA isn’t available for an interview, I had to ask questions to Baseball Prospectus’s Editor in Chief Ben Lindbergh for thoughts on what we can expect in the capital this season.
District on Deck: The article you wrote about your conversation with Colin Wyers mentions that PECOTA has a long memory and the Nationals aren’t far removed from an under .500 team. Is it the team’s win/loss record itself that makes a difference or is it the players histories (and in Washington’s case, most pieces are the same) that make it more conservative?
Ben Lindbergh: The players’ histories. Put simply, PECOTA generates its team-level projections by putting together player projections (with playing time determined by our depth charts), then adjusting for strength of schedule.
DoD: Throughout the book and in the playoff odds online, veteran teams like the Yankees are projected better than up and coming teams like the Nationals, mainly because aging veterans are projected to bounce back from off years and young players coming off their best years are expected to regress negatively. Is this a “feature” or a “bug” that PECOTA is more forgiving to players like Tim Lincecum and Dan Haren than they are optimistic about Bryce Harper and Gio Gonzalez
BL: Overall, it should be a feature. Regression to the mean is essentially a function of two things: sample size, and the distance from the mean. We regress younger players more because there’s more uncertainty about their true talent level.
DoD: On the list of Biggest Decline in terms of WAR on the PECOTA leaderboards, three Nationals (Adam LaRoche, Jordan Zimmermann and Gio Gonzalez) appear. Which would be the most problematic for the Nationals?
BL: LaRoche’s projected decline would be the biggest, and his resulting production would be the worst, so in a sense, I suppose that would be most problematic. If you’d asked me which player the Nationals could most ill afford to lose, though, I would’ve picked one of the pitchers, both because they’re projected to be better and because the Nats probably wouldn’t miss LaRoche much if they replaced him with Tyler Moore.
DoD: PECOTA doesn’t look at age in terms of the noted “jump” players get from age 19 to 20. Last year, PECOTA was very conservative when it came to Mike Trout and this year, expects a worse season from Bryce Harper when most see a chance for improvement. How do you balance PECOTA’s thoughts and your own thoughts and ideas?
BL: I refer to the projections as a guide, but not as gospel. It’s a good thing that the projections surprise us sometimes–if they only confirmed what we already thought, they wouldn’t be very useful. I think we have a natural tendency to assign too much weight to recent performance, which can cause us to buy into breakouts and collapses more quickly than we should. One of the biggest benefits of projection systems is that they can counter that bias. PECOTA missed on Mike Trout in 2012 (not that any projection system would have predicted a season like the one he had), but PECOTA’s conservatism when it comes to Trout actually looked prescient in 2011, when it projected a .686 OPS and he posted a .672. However, there are times when the projection system might be missing something important. For instance, PECOTA is predicting a bounceback for Dan Haren, but it doesn’t know about his significant velocity loss and the changes in pitch selection he’s made to compensate for seemingly diminished stuff. We do know about those things, so we can take them into account and adjust our expectations accordingly.
DoD: What PECOTA prediction to you look at and agree 100%? How about the opposite. Which one do you look at and think it’s a little off?
BL: The projections for Ryan Zimmerman, Denard Span, and Adam LaRoche match up pretty well with my expectations. Haren’s projection would probably be the one my own would most differ from, for the reasons I already mentioned. And I would be tempted to take the over on Harper.