While a win against the powerful (but fading) Texas Rangers has fans feeling a bit better, the fact remains that the Boston Red Sox have just gone 1-3 against the Minnesota Twins, the second worst team in the American League at Home and they are now just 4-4 on this current home stand. Given the way things have gone this season, the series loss to Minnesota should not come as a surprise.
This is a shocking turn of events for a franchise that has traditionally built teams that can take advantage of their unique environment and rack up the wins at home. You have to go back to 1995 to find Red Sox team that made the playoffs with a better winning percentage on the road. Last year’s team was the same at home and on the road (.556 winning percentage for both) and you have to go all the way back to 2002 to find another Red Sox squad that was better on the road than at Fenway. The last Red Sox team to finish the season over .500 on the road and under .500 at home was the 1980 team, which featured a 40 year old Carl Yastrzemski.
The reason for the Red Sox poor winning percentage at home is not surprising. Red Sox pitchers have been far worse at home than on the road. On the road, the team has a 3.82 ERA, which would be the fourth best mark in the American League, just ahead of the Angels. However, at home, they have a dreadful 4.65 ERA, that would be third worst in the league. Fenway is a hitter’s park, increasing runs overall by between five and seven percent, but the gap in ERA is far beyond the range of a mere park factor’s influence.
Digging deeper into the numbers reveals some surprising reasons for the Red Sox pitching woes in Fenway. Red Sox pitchers overall have a slightly worse strikeout rate at home (6.9 K/9) than on the road (7.4 K/9) but a better walk rate (2.9 home, 3.2 away), resulting in a better strikeout-to-walk ratio in Fenway. Fenway has a very minor park factor influence for walks and strikeouts, so the small variations here are probably nothing more than random variations. Red Sox pitchers (and fielders) have generally overachieved at turning balls in play into outs on the road, with a .278 batting average on balls in play away. While the team’s .303 BABIP at home is above league average (.291) it is less than what we might expect given Fenway’s influence. Where the Red Sox pitchers have really struggled is in preventing home runs at home. On the road, the team has been better than average (1.1 HR/9) at preventing home runs with just 0.9 HR/9 away. At home, they are worse, with 1.2 HR/9. That is a small enough variation to be considered random until you consider that Fenway suppresses home runs by about five percent. Considering Fenway’s influence, a league average team would allow just 1.0 HR/9 and a team that keeps the ball in the park as well as the Red Sox do when they are traveling should certainly be able to maintain the same rate while playing half their games in Fenway.
The entire Red Sox staff seems to be at fault here. Of the top six pitcher by innings pitched only Josh Beckett has allowed fewer home runs at Fenway (0.9 HR/9) than on the road (1.06) this season. The team’s three top lefties have all been crushed by long balls at home, which is not very surprising, given that the home run-suppressing effects of Fenway impact left-handed hitters to a far greater degree (lower LHH HRs by 8% and RHH by just 2%). Jon Lester has a 1.4 HR/9 rate at home and a 0.9 rate away. Doubront has a 1.5 HR/9 rate at Fenway and a 1.1 rate away and Franklin Morales, who has the least reliable numbers given his limited innings has a 1.5 rate at home and a 0.8 rate on the road. The effect is not just hurting lefties, however. Clay Buchholz, Alfredo Aceves and Scott Atchison all have much higher home run rates at home (though since Atchison has not allowed a homer on the road, that can’t really be helped in his case.
This is not par for the course for these guys, though. Lester and Buchholz have actually been better at preventing home runs at home than on the road before this season, while Becket has been worse. This could be a sign that regression will even things out at some point (though not necessarily this season), but it could just as easily be a warning sign. I try to avoid explanations that stray away from things I have concrete evidence for, but it would probably be remiss to overlook the pressure that pitchers have been under in
Separating the effect of the ballpark, random variation, and outside influence is going to be key to correcting the issue of winning at home. The Red Sox play half their games in one of baseball’s most unique environments. Throughout their history, they have done an excellent job of turning that into an advantage. On offense, they are still finding players like Cody Ross who fit Fenway perfectly, but the same cannot be said for pitching. Until the Red Sox start playing their best baseball in their own park, they are going to struggle to compete in the toughest division in baseball.