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How Does AT&T Park Affect Hitters?

July 10, 2010

Is AT&T Park really a death trap for hitters?

Color me biased, but there is absolutely no doubt in my mind that AT&T Park is one of the most beautiful stadiums in the game today.  Its location and dimensions are practically perfect in my mind, and I honestly can’t think of a ballpark I’d rather sit in to watch a game (aside from, perhaps, Seattle’s SafeCo Field).  Naturally, the park holds a very special place in my heart- it is, after all, the home stadium of my favorite Major League team.  Within the decade of its existence, it has already seen some historical events: most notably, Barry Bonds’ home run marks and Jonathan Sanchez’s No-Hitter.  There are others, of course, but those are the memories that come to mind the quickest for me.  I was there for Bonds’ 661st home run; my Father at 756.  I was there for the debuts of both Matt Cain and Tim Lincecum.  I guess you could say that I have something of an attachment to the park.  I have a lot of wonderful memories there, and every time I go to a game my excitement matches that of a child in Disneyland.

This is why I always take offense to the free agents that spurn the Giants’ offers to play for them.  Over the past couple of years, multiple high end free agent hitters- the ones that come to mind are Alfonso Soriano, Carlos Lee and Matt Holliday (I’m not sure about Jason Bay or Mark Teixeira)- have made it clear that they had no desire to play in San Francisco.  The free agent perhaps most open about his distaste for the park was Adam LaRoche, who declined a rather lucrative two-year deal and wound up signing a smaller one-year deal with the Arizona Diamondbacks.  Conversely, pitchers love to pitch at AT&T because of its expansive outfield.  This would be great if the Giants weren’t particularly good at developing pitchers- the problem is, they’re quite adept at developing pitchers and the exact opposite when it comes to hitters.  AT&T has garnered a reputation as being a severe pitchers’ park; a real death trap for hitters- especially for lefties not named Barry Bonds.  But is this true?

One of the beautiful things about sabermetrics is that it gives us tools with which we can begin to test these allegations.  In the case of park effects on hitters (or pitchers), we can look at park factors.  The concept of a park factor is rather simple: it is often nothing more than the ratio of runs scored at the park in question compared to all other parks in the league, in an attempt to give us a relatively accurate idea as to which parks have higher (or lower) run-scoring environments than others.  I’d like to expand on this notion, however, and look not just at the overall park factor- but how the park affects a player’s component batting rates, i.e. how much the park increases or decreases different hit types in addition to non-intentional walks and strikeouts.  By doing this, we can look at the way in which AT&T affects right-handed and left-handed hitters differently.

For this little “study,” I’m using five years of data (2005-2009).  I looked at the rates of individual offensive events at Mays Field (1B, 2B, 3B, HR, ROE, NIBB, HBP, SO) compared to the rates at all other parks in the National League.  The park factor formula I’m using is the one Brandon Heipp outlined in his incredible park factors article, regressed (10%).  I would also like to note that all components are regressed the same.  This is admittedly not the best way to go about it, but I’m uncertain as to what the “proper” or recommended regression would be (I’ll leave that up to the Mitchel Lichtmans of the world to determine).  But, I digress.  First, the right-handers:

Overall, we’re looking at a rather subtle effect on right-handed hitters.  The park is exactly neutral towards singles, and is essentially neutral with doubles and ROE.  Personally, I’m a bit surprised to see the doubles park factor favoring the pitcher– you’d think that a park like AT&T would allow not just more triples, but more doubles as well.  This isn’t the case, at least for the righties.  All in all, we’re looking at a park that seems to suppress right-handed production.  Now, how about those lefties?  Do the dimensions of the park affect them differently?

Now we’re beginning to see some more extreme effects.  Lefties see a very subtle increase in singles and doubles, with a gigantic leap in triples and an equally devastating drop in home runs.  It is also, by my estimations, the most difficult National League park for left-handed hitters to hit home runs.  Like righties, we see a very similar decrease in walks and strikeouts for hitters.  So, this means lefties are affected more than righties, correct?

If we apply the component park factors to a standard left-handed or right-handed batter’s line and figure the player’s Runs Created*, we can see how much the park influences a player’s overall performance.  In other words, can look at the sum rather than the parts.  A league average right-handed hitter creates 83 runs in 700 plate appearances in a neutral environment.  At AT&T, he creates 80 runs in the same amount of plate appearances.  So a player performs at 80/83 = 97% of the league average (80/83 is actually .964; rounding is different).  This means that the overall park factor for a right-handed hitter is 0.97.  For left-handers?  The league average lefty creates 87 runs in 700 PA; at AT&T, he creates 84 runs.  Once again, the overall park factor is 0.97.  In other words, AT&T Park generally affects left-handed hitters and right-handed hitters the same.  The actual difference between the two, if we want to get into specifics, is 0.0005493 in favor of lefties.  So…yes, the park absolutely affects a left-handed hitter’s home runs more than a right-hander’s.  But the overall effect is virtually no different.

Hitters are absolutely right- AT&T Park certainly does, generally speaking, favor pitchers over hitters.  But it’s not a drastic effect by any means, and I don’t think it warrants a hitter demanding the Giants to overpay when bidding for his services.  We also have to keep in mind, though, that not all hitters will be affected the same.  Barry Bonds still mashed while at AT&T, and some hitters won’t see much of a change (if any) when transitioning to the park.  Aubrey Huff is a recent example of this.  If you’re a left-handed pull hitter, chances are you won’t see much of a decline in your home run rate- and the same is true for right-handed hitters.  And if you’re a left-handed hitter and have a ton of speed, chances are quite good you’ll be seeing a huge jump in triples (Carl Crawford, I hope you’re reading this).

*By Runs Created, I am referring to a player’s absolute linear weights runs created.  The exact formula used is reconciled to match the National League’s total runs scored from 2005-2009:

LWTS_RC = .476*1B + .778*2B + 1.072*3B + 1.419*HR + .494*ROE + .309*NIBB + .177*IBB + .337*HBP – .099*(AB – H – ROE – K + SH + SF) – .112*K
12 Comments leave one →
  1. Bradley Emden permalink
    July 11, 2010 5:32 AM

    What if you factor out Barry Bonds from the equation?

    • triplesalley permalink*
      July 11, 2010 7:31 AM

      Excellent question!

      One of the reasons why I kept it to the last five years rather than extending back further was due to Bonds. Since Bonds accounted for roughly 3.1% of all plate appearances at AT&T from 2005-2009, the effect he may have had is minimized. When I first started fiddling around with component park factors, I found that he seemed to throw off the non-intentional walk rate by quite a bit when I included the 2000-2004 seasons.

  2. July 17, 2010 2:12 AM

    Great article! I love statistics, but I have a hard time following a lot of the sabermetrics, so this was very well written and accessible. Thanks!

    • triplesalley permalink*
      July 17, 2010 2:33 AM

      Thank you! I’m glad you got something out of it. 🙂

  3. sam permalink
    July 18, 2010 5:29 AM

    where did u, or might i, find hitting stats for specific parks? specifically, i saw tonight that buster posey hit a home run to right field, and i got curious how many times (if ever) this has happened at AT&T park? any thoughts?

    • triplesalley permalink*
      July 18, 2010 5:53 AM

      You should be able to find all of that data at All of the data that I used for this article and for all of my park factors can be found over at under “splits,” but they don’t give the exact location (which is unfortunate!).

  4. sam permalink
    July 18, 2010 6:06 AM


    • triplesalley permalink*
      July 18, 2010 6:25 AM

      You’re very welcome! I hope that helps some. 🙂

  5. sam permalink
    July 18, 2010 6:41 AM

    i’m wondering if there’s any place that keeps stats on the location of home runs hit–to left, center, or right field? I started looking at Jeff Kent’s stats at AT&T park and thought he’d be a likely candidate for another righty to have possibly homered to right field in that park, but do you know where (or if) anyone might have that?
    thanks again!

    • triplesalley permalink*
      July 18, 2010 8:24 AM

      Baseball-Reference’s splits section would still be your best bet- all I can gather from it is Kent pulled 58% of his HR, 36% to CF, 3% to RF, and another 3% to an “unknown” location. There’s no specifics as to where they were at AT&T- you’d have to parse through the Retrosheet data to find exactly what you’re looking for.

      You can also find current day hit locations here:

  6. July 21, 2010 9:43 PM

    This was an great post. I really like how your broke the stats for both lefties and righties. As as a Giants fan it really irritates me how AT&T is perceived. Yes, it’s a pitchers park but it isn’t a death trap. I understand that overall based on your stats that park affects righties and lefties the same and that the difference is slightly under the rest of the league however, I feel that most power lefties look at that .84 for homeruns and it scares them off. Especially when it comes to those windy nights it can really be a task to hit one out to McCovey’s Cove however, the Giants organization needs to the focus off of bringing in a power hitter via free agency. If it’s a trade fine but, we need to focus on bringing in hitters that can hit doubles and triples, and speed (Carl Crawford and Jayson Werth ). I would rather have two of these players then one power hitter. They can potentially be cheaper. Love the blog though I will look forward to your future posts.

    • triplesalley permalink*
      July 22, 2010 8:00 AM

      Thanks for stopping by! I hope I can continue to put up posts to your (and everyone else’s) liking. 🙂

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