Why Do Some Players Play Better At Home?

September 15, 2010

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If you don’t realize that I’m a big baseball fan, you’re new around here.  I like baseball as much as Evan likes Evernote – and nearly as much as Lazy Man hates Mona Vie.  I subscribe to MLB Extra Innings, get Sports Weekly in my mailbox every week (just for the baseball coverage), and pre-order Ron Shandler’s newest book every year.  I’d say that it borders on an obsession, but I have to be honest with myself – it crossed the threshold many years ago.  To paraphrase the quote from Jerry Maguire, it had me at “play ball”.

As a fan of the Colorado Rockies, I’m acutely aware of the differences between the offensive numbers the Rockies compile at Coors Field versus the numbers they compile on the road.  Although the installation of a humidor several years ago has cut the gap somewhat, the team typically achieves an OPS (on-base-plus-slugging) of somewhere between 100 and 150 points higher at home (the 220 point differential this year is an outlier).  The typical Major League player has an OPS 31 points higher at home – so Coors Field clearly aids the Rockies hitters.

Chipper Jones of the Braves has thrust his own opinion into this issue into the spotlight, suggesting that Carlos Gonzalez’s numbers are not legitimate due to CarGo’s massive home/road splits.  Never mind that Chipper enjoyed a 244 point differential in his 1999 MVP season.  Apparently dramatic splits are OK, as long as they aren’t compiled by a Rockies hitter.

Of course, a couple of things often get ignored.  First, the home/road disparity can be skewed by the unbalanced scheduled.  The Rockies play more games in San Diego’s Petco Park (a pitcher’s paradise) than the Cubs do, for example (this is also why ESPN’s park factors are flawed).  The second is an effect that has been theorized but not proven – that there is a Coors Hangover effect that negatively affects Rockies players on the road.  The gist of this argument is that Rockies hitters get lulled into the flatness of breaking pitches (curve balls, sliders, etc.) at home and are not prepared for the sharper breaks at lower elevations.  A couple of years ago, I analyzed some data that supported this theory.  In 2008, the Rockies hit line drives on 23% of balls they put into play at home, and just 19.6% of balls they put into play on the road – an indication that they are actually making more solid contact at home, rather than simply enjoying the fact that the balls travels further in thin air.  This was an incomplete study, as I did not analyze the splits for other teams.

More importantly, players on the same team are affected differently by the park.  Carlos Gonzalez of the Rockies has an OPS 400 points higher at home this year.  Troy Tulowitzki has a more modest 138 point differential.  I struggled to find a comparable player to CarGo – but the most notable lefty who played predominately in the post-humidor era and had some power is Brad Hawpe (Todd Helton and Larry Walker played a lot of games pre-humidor).  Hawpe has a career differential of about 50 points – not much more than the 31 points for the average MLB player.  The home/road splits are all over the chart – without a lot of logic to the distribution.

I have theorized for many years that there are mental, psychological, and social factors that come into play.  Some players will be consistent studs at home, while others will stink it up in front of the home team fans and dazzle on the road.  Why?

Unique aspects of the park – Every park has unique aspects.  The most notable is perhaps the Green Monster in Boston’s Fenway Park.  The left field wall is a stone’s throw from home plate – but looms 37 feet high.  A play who can tailor their swing to hit high fly balls to left field will get homers at home and harmless outs on the road.  It’s not always as easy as flipping a switch when you go on the road – but if this player were traded, they would likely change their swing to remove the uppercut.

A less notable feature of each park is the batter’s eye in center field.  You may notice that there are never any fans sitting in dead center field, and that this area is always a solid color.  This is to provide a visual background that allows that hitter to see the ball after it is pitched (imagine trying to see the balls with fans in the background, wearing a variety of colors).  A player may become accustomed to their park’s hitter’s eye and hit better with it in the background.  The ability to adapt your style to suit the ballpark is a skill, not a fluke – and it’s portable to a new home environment.

Climate – Call it the Favre factor.  Some guys are going to prefer cooler climates while other prefer warmed climates.  The data do exist to analyze climate data (the box score contains the temperature at the start of the game), but I haven’t seen much work on this topic.

Family life – Everyone is happier when they are around loved ones.  I would theorize that players in happy relationships will do well at home, and players in bad relationships (or no relationship) will not do as well.  If a marriage is turning from bliss into hell, I would expect a player’s home/road splits to become more road-favorable.

Dining and Entertainment Options – I like having my favorite restaurants around.  Plop me into the midst of a vegan-leaning area and I would not do well.  A happy belly is a happy ballplayer.  Likewise, a player who enjoys mountain hikes is going to be happier with his home base in Denver and a fan of Broadway shows will enjoy New York.  Put the mountain hike guy in New York City and the Broadway guy in Denver and neither is as happy.

Community involvement – Some players are much more involved in the community than others.  Some players are more like hired guns – coming in to do a job, and then leaving town the day after the season is over.  I would expect the more involved players to do better at home, because they have a good feeling about the city.

Fans – And, of course, the player’s relationship with the fans.  If the fans are vocally supportive of a player, I’d expect the player to out-perform the park factors – although it’s possible that some players could try to hard and do worse because of the fans.

Really, all of this boils down to one thing.  Players who feel more “at home” in their home city should have better splits than a player who is more neutral about the surroundings.

I haven’t had the time to compile an all-inclusive list, nor have I had the time to do any statistical analysis of the theory.  What other factors do you think can affect a player’s home/road splits?

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