Throughout the season, it has seemed like the Yankees either score a ton of runs or get completely shut down every game, and there seems to be little middle ground. In the second half, the Yankees have looked like a World Series caliber offense one week and looked like they were coming crashing down to earth the next. When things are going well, the Yankees will hit home run after home run and drive runners in from scoring position. When things are going badly, the strikeouts will pile up and runners will be stranded.
Of course, any fan who follows his or her team on a day-to-day basis can go from planning the World Series parade to thinking about rebuilding within the span of a few days. But with the Yankees, the roller coaster ride has actual statistical basis. Going into Friday's games (September 4), the Yankees had the highest variance in runs scored, and it isn't very close:
Variance measures how close a set of numbers is to their average. At 15.5, the Yankees variance in runs scored is almost 25% above than the next highest Toronto Blue Jays. The Seattle Mariners might not have the most high-powered offense, but it is more consistent than every other team, as their variance is the lowest in the MLB.
One could draw several explanations and conclusions, both positive and negative, from this trend. On three occasions this season, a team has scored 20 runs in a game, and the Yankees have done it twice. The obvious one is that teams with more offense are going to stray further from the mean because they put up the occasional double digit onslaught. Another possible explanation for this phenomenon is the old baseball adage that hitting is contagious. Whether there is statistical evidence or not, people have said it for generations. This might be due to the fact that teams whose starters get hit early have to go to their less skilled middle and long relievers, who continue to get shelled as the game goes on.
Another potential reason is the short porch in right field. More so than ever, the Yankees have taken advantage of the shallow fence in right, stacking the lineup with left-handed hitters who can gun for the 314 FT. sign. If almost every hitter in the lineup is focused on pulling the ball over the fence, it can effectively turn an entire team into three-outcome hitters, who will often go on extremely hot and cold streaks.
Going forward, the Yankees streakiness should serve to increase the sense of urgency with which they chase the division title. If the season ended today, the Yankees would face the Texas Rangers at home in a Wild Card playoff. The Rangers could send lefty Cole Hamels out for a one-game playoff in the Bronx. If the Minnesota Twins win the Wild Card, they could use Tommy Milone and hope he can keep the Yankees in the ballpark. Still, their best bet is in a five-game series, where the law of averages has more time to do its magic. With seven games remaining against the Blue Jays, lets hope the double digit scoring Yankees show up over the final month.
Data is courtesy of Baseball Reference.