FanGraphs: Sullivan: Moving in the Fences: A History

Fence Busters…and the repairs that go along with it.

Colorado might be the place that most made people aware that baseball works differently in different ballparks. It was pretty hard to deny the fact that, in Colorado, hit baseballs just took off. Since people became aware of Colorado playing in a hitter-friendly stadium, many people have also become aware of San Diego and Seattle playing in pitcher-friendly stadiums. Petco Park and Safeco Field are two of baseball’s newer parks, and to date they’ve played reasonably extreme. Because of their established pitcher-friendliness, both Petco and Safeco are having their dimensions adjusted this offseason. The idea isn’t to make the ballparks hitter-friendly — it’s to make them more hitter-friendly, or basically more neutral. You bring the fences in, and it follows that offense ought to go up.

Yet it’s interesting what we can observe in recent history. I can identify four instances in which fences were moved in somewhere with the idea of helping the hitters. Between 1994-1995, the Royals made adjustments at Kauffman Stadium. Between 2002-2003, the Tigers made adjustments at Comerica Park. Between 2005-2006, the Padres made an adjustment at Petco, which obviously wasn’t enough. And, between 2011-2012, the Mets made adjustments at Citi Field. Though simple park factors are imperfect and while in certain cases we’re working with limited data, the relevant numbers are of interest.

...Evidence that bringing in the fences might have both intuitive and counter-intuitive effects. Park effects are complicated, meaning park adjustments are complicated. It’s easy to understand how nearer fences can mean more home runs — fly balls have to travel less distance. But that can also have other effects, like cutting down on doubles and triples, and there isn’t a perfect correlation between homer rate and run-scoring rate. If you have a pitcher-friendly ballpark, the answer might not be as simple as moving the fences closer to home plate. These things are tough to project.

Of course, what’s happened before after different adjustments might not mean anything for Petco or Safeco in 2013. No ballpark has done exactly what those two ballparks are doing. And the adjustments are being made in large part for psychological reasons — the Padres and Mariners are tired of bumming hitters out — so run-scoring might not be the key. Even if the run-scoring rates don’t change, it could be a psychological success if the home-run rates improve, because hitters want to be rewarded with dingers for their long fly balls. A place where it’s hard to hit homers feels different from a place where it’s average to hit homers, but still hard to score runs. There’s a lot going on here.

Here’s one thing we can say: going forward, it’s probably going to be easier to homer in San Diego and Seattle. Here’s one thing we can’t say: going forward, it’s probably going to be easier to score in San Diego and Seattle. That might well end up being true, but it would be wise to wait for statistical evidence. The historical record is a curious one.