A Different Look At Run Differential

"The Angels may well finish with the best record in the league. It won't mean they're the best team." 

So says ESPN's Rob Neyer in his posting from September 11th.  He feels that the Boston Red Sox are the best team in the American League partly based on Run Differential.  His point is since the Red Sox outscore their opponents at a higher rate than the Angels, they're the better team.  And you know, I agree with that.  If a team scores more runs than they give up, they're a good team.  And if a team scores a lot more runs than they give up, they're a really good team.  The Red Sox's Run Differential as of today (9/22), is +159 (second only to the Chicago Cubs), meaning they've outscored they opponents by 159 runs.  The Angels Run Differential is +75, about half as good as the Boston's, but when you look at the numbers a little closer, there's one thing Neyer's missing in his assumption; Home and Away splits.  I think if a person is going to use Run Differential as a metric to compare teams, you should give more weight to a team's road Run Differential because this gets rid of any home ball park effect, and compares numbers that cover basically the same park effects.  The comparison of road numbers would get rid of the imbalance for teams that play in a hitter-friendly park, such as Texas, and teams that play in pitcher-friendly stadiums like San Diego.  Here are how the Angels and Red Sox compare when looking at Run Differential splits:

The Red Sox love home cooking.  They've outscored their opponents by 130 runs and are 30 games over .500 at Fenway.  Compared to the Angels in Anaheim, the Red Sox are the much better home team.  Things change when the Red Sox go out on the road.

The Sox suck when they leave Boston.  Almost their entire differential in runs comes from their excellent play at home.  When you compare the Angels numbers, their Run Differential is roughly the same regardless of if they're home or away from Anaheim, while Boston is a completely different team when they play on the road.    

As of today, Boston is 1.5 behind Tampa for the division lead, and would be the wild card team heading into the play-offs.  As the wild card team, their opponent in the first round of the play-offs would be Anaheim who is 5-1 at Fenway and 3-0 in Anaheim.  The Angels will have home field advantage, at least during the first round.  This advantage is just one game, but based on the numbers, that one game's location is very important to the Red Sox, while it doesn't look like it matters to the Angels.  My prediction: Angels win the first two games in Anaheim, lose game 3 and then win the series in the fourth game.

I absolutely respect Rob Neyer and I usually agree with his analysis, but in this instance I think he's wrong in thinking the Red Sox are the better team.