I don’t pretend to know a whole lot about how park factors influence player performance, but I am really curious about it. I have always wondered how player movement has affected player performance and obviously the degree of friendliness of the home park has something to do with that. I decided to see if I could figure out just how important it might be to look at home/road splits when evaluating a potential acquisition. There has been quite a bit (some would say too much) discussion about this issue on the board lately, so I thought I would dig up some data and see if it spoke to me.
The first decision was to figure out whose park factor ratings to use. I didn’t really make too much effort to identify the definitive dataset as I located one on mlb.com that seemed useful. It was sortable by a bunch of different statistics and included data for 2005-2007. Since a lot of the discussion here has been around getting an additional bat, I thought OPS would be as good a metric as any to use as a baseline.
So I sorted the data by OPS and took the top five hitters parks, the middle four (there just happened to be four with an OPS index of 100) and the five least hitter friendly parks. Then I went to each of the home teams associated with these parks and looked at their top five OPS guys as a sample. My ultimate interest was to see whether these boppers tend to hit well in their home parks or whether the park factors dominate.
Some of the rankings may be a little surprising as the top five hitters parks for OPS are, in order: 1) Coors Field (COL); 2) Chase Field (ARI); 3) Citizens Bank Park (PHI); 4) Great American Ball Park (CIN); and 5) Cellular Field (CWS). Wrigley Field and Kaufmann Stadium tied for sixth. I expected to see The Ball Park in Arlington (10th) and Camden Yards (11th) rated a little higher.
The results for the hitter friendly parks were mostly as expected, but a little bit mixed. I know my methodology is mostly suspect here, but it seems safe to say that Coors Field is still a great place to hit the baseball. The top five OPS guys for the Rox are currently enjoying a 21% higher OPS at home than on the road for 2008 and the four-year average, including 2008 data, is 20.3% higher. Every Rockies player evaluated had a significantly higher OPS at home each year with the lone exception of Brad Hawpe’s remarkable road OPS of .966 in 2006. The much discussed Matt Holiday has a 26.1% boost over the period which is the single highest differential of any of the 70 players studied.
Arizona was a little harder to analyze as they have a number of young players without a lot of track record in the home park. However, the effect seems to be a pretty strong one as the average boost for the study period was 17.3%. This data is somewhat skewed by Justin Upton’s 2008 delta of a .550 road OPS and a 1.001 home OPS. Another player coveted by many VEBsters, Orlando Hudson, received quite a favorable boost of 19.8%. So look out MO, the guy has never put up an OPS on the road better than .734.
Philadelphia was actually quite puzzling as I expected to see a huge advantage to the Phils here, but it doesn’t really look that way. While Ryan Howard is doing 15% better at home this year, his four-year average is only 6.7% better. During his MVP season in 2006 he actually put up a slightly better OPS (1.089!!) on the road. Chase Utley has done quite well in the home yard, especially in 2007, but has only gained an 8% advantage since 2005. Pat Burrell is the mystery man here as he actually is hitting a whopping 42.5% higher on the road with an OPS of 1.163 for the season away from home. However, he hit .221 higher at home last year, so go figure. Over the four-year period he is at -1.5%. Neither Shane Victorino nor Jimmy Rollins hits particularly well at home, so the Phils net advantage is a pretty insignificant 3.4%.
Cincinnati’s numbers bounce around quite a bit from year to year and none of their top five OPSers has an advantage of more than 6% and the team average is 4.7%. The Chicago White Sox are similarly uninteresting with pretty small deltas, but Jim Thome is doing much better on the road this season.
The four parks in the “neutral” category are: 1) Minute Maid Park (HOU); 2) Comerica Park (DET); 3) PNC Park (PIT); and 4) Turner Field (ATL). A little surprised here as I would have expected each of the NL parks in this group to be slight hitters’ parks. I don’t really follow the AL much, but I have a recollection that the fences were moved in at Comerica somewhat recently – don’t know if it was since 2005 or not.
This is the group that ought to give some hope to the folks who think good hitters will hit better at home. There is no park bias to interfere with the results, so let’s take a look at the data.
Carlos Lee and Miguel Tejada both love Minute Maid with home field advantages of 13.8% and 17.2% respectively. Not a surprise that RH power guys would do well there. The bad news for Tejada is he is only OPSing .676 on the road. For all the damage I have seen Lance Berkman do in Minute Maid, he seems to hit equally well on the road for a net advantage of 0.8%. The overall team advantage is 6.9% or about .050 points of OPS.
I am guessing the fences were moved in Comerica after the ’06 season as that was the year that all their boppers did much better on the road. Since then, Miguel Ordonez has been a monster at home with 1.129 and 1.038 OPSes the last two years. Cabrera is .089 points higher at home and Guillen is hitting over 22% better at home this year. I think this park has morphed from a pitchers’ park to a hitters’ park, even thought it shows neutral in the data.
PNC looks pretty neutral with three of the top five guys showing better road splits in 2008 and 2 out of five doing better on the road in 2007. Only Ryan Doumit’s huge home field advantage of 30.4% this year and 19.6% in 2007 keep the Buccos in positive territory with a slight 4.4% boost
The final neutral park is Atlanta’s Turner Field. The two longest standing members of the top-five club are Chipper Jones and Brian McCann. Chipper has actually hit better on the road in two of the last four years, but when he is hot at home he really gets it done. His 1.220 OPS at home this year and his 1.056 in 2005 make the home field a slight advantage for him. McCann is essentially even year to year. It will be interesting to see how the recently traded Mark Texeira fares for the Angels as he loved hitting in Turner Field. His .957 OPS at home was .113 higher than his road number. Overall, the boppers for Atlanta hit 5.7% better at home.
Now for the pitchers parks (lowest OPS first): 1) Petco Park (SDP); 2) Nationals Stadium (WSH); 3) Hubert H. Humphrey Metrodome (MIN); 4) McAfee Colliseum (OAK); and 5) Busch Stadium (STL). I think everyone is aware that Petco is by far the worst hitters’ park in the bigs – just ask Jimmy Edmonds. However, I was surprised by both the Metrodome and Busch being in the bottom five.
Our own Cardinals are the best evidence I can find to counter the argument that hitters can adjust to their home parks and overcome park factors. The top five in OPS on the Cardinals are Pujols, Ludwick, Ankiel, Glaus, and Schumaker. Every one of them hits better on the road – most of them significantly better. Albert managed to hit better at home during the first year of Busch III, but fell to a .886 OPS, or 23.8% below his road OPS, in 2007. He is better this year, but still puts up better numbers away from Busch. While both Ludwick and Ankiel put up nice numbers at Busch in limited action last year, it is a different story this time. Ankiel is .074 better on the road and Ludwick is .091 better. Glaus is getting better at home, but is still .106 better away from home. Skippy is .112 better, or 15.3%, on the road as well. Total for the group since opening of Busch III is -7.8%.
Just in case anyone out there is still reading, if you discount Matt Holliday’s road performance by 7.8% it is not pretty. His career OPS on the road is .792., so if you discount that by 7.8% he would have a projected home OPS of .730 and a total OPS of .761. If you use his career best OPS of .863 and discount it you get a .796 home OPS and a combined total of .832. Really not what I want to spend a bunch of prospects and $13.5 M on.
Oakland is another one that is hard to get a handle on because they churn their roster so much. One thing to consider for all you Mark Ellis fans: he has a 16.5% home park penalty to his OPS so he is probably a better hitter than we give him credit for. His road OPS this year is .867. Otherwise, the A’s (with very questionable data) seem to hit slightly better (2.3%) at home.
Joe Maurer must get a lot of turf hits, because he absolutely stars at the Humphrey Dome. His OPS at home this year is .244 higher and last year it was .204 higher. Justin Morneau would be much improved away from the HeftyDome as his career OPS is 10.3% lower at home and has been significantly lower three of the last four years.
I don’t have much to say about the Nationals as their stadium is new this year and they have a bunch of stiffs hitting there. However, the stiffs like to take it on the road as they hit 14.7% lower at home.
I feel sorry for Missouri native and recent 3rd round Padre pick Blake Tekotte. If he is fortunate enough to make it to the show I hope he gets traded first. Petco is brutal, just ask Adrian Gonzalez. He is carrying a 25.3% drag on his OPS at home. This guy has put up a .900+ OPS on the road each of the past three seasons, but he gets no love. Ditto for Brian Giles who has a 17.6% millstone around his neck as well. If you take Gonzalez’ .935 OPS average on the road for the last three years and give it the Matt Holliday 26.1% boost that calculates to nearly a 1.200 OPS at Coors field. Now, obviously some of Gonzalez’ road games are at Coors already, but you get the idea. As a group the top five OPS guys are down 10.5% in the history of the park even though Scott Hairston has managed a .906 OPS at home this year.
So, what does all this crap actually mean? Probably nothing if you are into rigorous statistical analysis, but it tells me that the comforts of home are probably worth a little lift to the numbers, but probably not a significant amount. Maybe around 5% or so.