Arguably the most far-reaching impact of sabermetrics is in the use of park factors to put player performance in context. Throughout baseball history, players, fans and executives knew that certain parks changed the game and the statistics, from the Polo Grounds' horseshoe outfield to Yankee Stadium's short porch to the vast expanses of Sportsman's Park in St. Louis. It was statheads who started hanging numbers on those elements, though, enabling us to evaluate players more accurately.
One of the most important things we learned was that ballpark factors bounce around from year to year, owing to the half-season nature of the data (81 games a year in any park) and the changing personnel who play through. Serious analysts have determined that you need three years to evaluate a park, and some use as many as five in setting their adjustments. All agree that using one-year park factors is a mistake -- too small a sample to rely upon.
Of course, perceptions can be hard to change, so when you think about Minute Maid Park in Houston, you think of it as a bandbox, because in 2000 it was the fifth-easiest park in which to hit a home run, and like playing on the moon after years of games in the Astrodome. In 2001, though, it played as both the hardest park for homers and run-scoring in all of baseball. Since then, it has generally rated as a slight hitters' park, and its three-year factors reflect that. You see this kind of jumping around all over single-season ratings; Cleveland's Progressive Field was the best hitters' park in the game based on 2001 data, but it was the second-best pitchers' park in baseball based on 2009's. Some parks routinely occupy one end of the spectrum -- Petco Park in San Diego has always been great for hurlers -- but for the most part, one year of data is unreliable.
Think about the Mets' new home, Citi Field. All of the coverage in 2009 focused on how tough it was on the Mets' hitters, what with the deep outfield and high walls. And yes, it did play as a pitchers' park, 6 percent more difficult for run scoring. But home runs were, in fact, slightly easier to come by at Citi Field than in other parks, by about 4 percent. The Mets' injury problems last season, which would have made them a lousy homer team in Williamsport, were why they didn't hit for power at home. They didn't hit for power anywhere, because they didn't have the personnel for it. Citi Field was a scapegoat.
So far in 2010, Citi Field has been tough on hitters and home runs, but if one season is too small a sample, one quarter of one season is useless. Certainly the Mets are bucking the trend, with a higher slugging average and
Mets fans obsessed over the park a year ago because of how poorly their boys played in it, with much of the focus on
Wright has continued that trend in 2010, and in fact, appears to have permanently changed his approach at the plate. Over two years, Wright's strikeout rate has doubled with only a small uptick in his walk rate. He seems to be consciously trying to hit the ball out of the park now, trading line drives for fly balls, swinging and missing more both at pitches in and out of the zone. The change hasn't been a positive one; Wright is still a productive player, but at a level below his 2005-2008 peak, as the lower batting average and OBP hasn't been matched by a rise in walks or isolated power.
No player doubles his strikeout rate over two years without it being a change in approach or a physical factor. Wright, it seems, reacted to the Mets' loss of power last season by taking it upon himself to hit like a cleanup guy, and in doing so, has made himself worse. The Mets don't need Wright to hit home runs; they need him to be the best player he can be, and that means getting back to what made him a star through his peak, being selective at the plate and hitting line drives into the gaps.
The middle of the Mets' lineup isn't their problem. David Wright and Jason Bay are productive hitters who get on base and hit for power, perfectly capable of being the 3-4 on a championship team. The Mets' problems are elsewhere, and obsessing over the numbers of their very best players distracts from addressing the real problems with the offense, such as the