There’s a story that has been told about Petco for years. It’s about a ballpark that was built too darned big. In this story, all the long fly balls get caught at the warning track. “You have to change completely there,” said Ryan Klesko at the beginning. “You have to take the loft out of your swing. Will they admit that they were wrong? No. Will they bring in the fences? No.” This is the story. This story may take a twist next year, as the team explores bringing the fences in. That should fix it!

Quietly, though, there has been another story playing out at Petco. It goes like this: the Padres’ hitters this year are the second-worst in the National League on balls hit on the ground. The Padres’ pitchers this year are the third-best in the National League on balls hit on the ground. This has been going on for years, and Ryan Klesko never said a freaking word.

These are the rankings, since Petco opened, of each park’s groundballs by batting average. For instance, this year Padres hitters and Padres opponents have a .218 batting average, and a .239 slugging percentage, when they hit the ball on the ground. Only four parks’ groundballs have produced less offense this year; in St. Louis, groundballs have produced a .262 batting average and .289 slugging percentage, or five more hits, seven more total bases, on 158 fewer grounders hit.

  • 2012: 26th
  • 2011: 30th
  • 2010: 30th
  • 2009: 30th
  • 2008: 22nd
  • 2007: 30th
  • 2006: 28th
  • 2005: 25th
  • 2004: 27th

During the nine seasons since the park opened, hitters in Petco have hit .217 and slugged .235 on groundballs. No other city is within 10 points of that batting average, or within 11 points of the slugging percentage. On average*, San Diego groundballs have each year produced:

  • 19 fewer hits than 29th-ranked Oakland;
  • 46 fewer hits than median Cincinnati;
  • 118 fewer hits than top-ranked Detroit.

So those are some facts, and now we’ll discuss a little bit of the unknown, and then we’ll be done.

Last summer, the Padres’ head groundskeeper, Luke Yoder, spoke to the San Diego chapter of SABR. Says Geoff Young, “although he acknowledged that a grounds crew can affect a field's playability, he didn't get into specifics regarding Petco.” A request through the Padres’ media department Tuesday wasn’t immediately responded to. So it’s not clear whether the Padres’ ballpark, the Padres’ climate, or the Padres’ grounds crew is responsible. Here’s Union-Tribune columnist Bill Center, a year ago:

"You hit on a point there. Petco Park has a finely manicured infield. One of the best in the game. But it is also softer than most infields. Ground balls are much less likely to get through the grass and the dirt. You don't see choppers bouncing over infielders heads in San Diego. Luke Yoder's crew might be too good at their jobs."

“Too good at their jobs” implies that Petco’s low-offense environment hurts the team. That’s a leap. That’s a leap I wouldn’t necessarily agree with. Along the same line, here’s another U-T writer, Tim Sullivan, suggesting that the solution to Petco (again, if Petco actually needs a solution) is changing the surface.

Plastic grass is to batting averages as the microwave is to meatloaf. Whatever it lacks in aesthetic appeal — and that’s virtually everything — artificial turf never needs mowing and almost always means bigger bounces. It turns ground balls into singles and singles into gappers.
Installing the stuff in an outdoor ballpark is a terrible idea, of course, but it might be the germ of a better one: changing a playing field without disturbing its dimensions.

An artificial surface wouldn’t actually be such a simple fix. Toronto’s Rogers Centre, at .227, has the third-lowest batting average on grounders since 2004. Tropicana Field, at .235, has the ninth-lowest**. There might not be any simple fix. Maybe it’s just a result of playing in San Diego. I don’t mean “maybe” in the sense that it may be. I mean “maybe” in the sense that, at this point, I have no idea. It could be. Anything could be. For all I know it could be f***** magnets, how do they work? I do know the Padres’ offense finished last in the NL in OPS on grounders in two of the three years before moving to Petco, so the continuity here seems to run through either San Diego or the Padres as an organization, not just Petco.

And production on grounders isn't the biggest driver of offense; we're talking about a few lost hits per regular each season. But it’s sort of hysterical that Petco Park, which might be the most difficult park in the majors for fly balls, is also by a pretty wide margin the most difficult park in the majors for grounders. You rarely saw Ryan Klesko ground out to second base, then unleash his frustration to the media about Petco’s unfair infield. But after nine years, we could say with pretty good confidence that it would have been justified, and will likely continue to be justified, new park dimensions or not.

*more accurately, in nine years Oakland grounders have produced 173 more hits, on 262 batted grounders; Cincinnati has produced 410 more hits, on 16 fewer batted balls; and Detroit has produced 1,061 more hits on 776 more batted balls.  

**Here are all the cities, ranked, if you want to stare and look for trends. Those include cities that have changed parks. They exclude Montreal’s single season, and the half-season of Marlins Park.

Thanks to Bradley Ankrom for research assistance.

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Sam, I think you said it best with "could be". Really nice investigation, but what really intrigues me now is a comparison with the other two SoCal parks and how low they rank on this list. All have roughly the same climate and are all described as "expertly manicured", but SD is closest to the ocean.

I think you do have a point here, but it'd be nice to follow up with direct comparison's to Dodger and Angel Stadiums, which are ranked close to each other about 20th.
In Toronto (where turf glare is a problem for the fans, i.e. me) ground balls bounce higher, making it easier for the infielder to snag it and to make the throw.
maybe if they let the infield go, like the rough at the U.S. Open, fielders will have difficulty finding the baseball, and GB BAs will improve.
"You rarely saw Ryan Klesko ground out to second base, then unleash his frustration to the media about Petco’s unfair infield."

Sam Miller continues in his bid to become my favorite BP. writer. Love it!
Informative and entertaining. Thanks!
Great work, Sam.
Very interesting.

The other thing about Petco and bringing in the fences is that the dimensions really aren't the biggest problem: it's the weather.

For whatever reason, the cool, marine layer that's there in 99% of night games seems to kill fly balls. For such a big park you'd expect a ton of doubles...but no, not so much.

In the daytime, Petco plays just fine.

In the end, whether it's the infield or the weather, bringing in the fences will add home runs, but bringing them in too far could bring a weird imbalance -- almost no doubles or triples and even a reduction in singles as the outfield could play in even more.
Very interesting article.
Any chance Jeter's low defensive metrics are a product of the infield as that of NYA is the third most offensive.
I'd love it if you were on to something here, but I believe some of the most compelling research on Jete's defensive inadequacy has used as a barometer the fielding metrics of other NYY shortstops.
Replace the stadium lights with heat lamps and the problem is solved....