Boston's bullpen is nothing special - 10th in ERA this season. Detroits also not special - 12th. Now, what is interesting is that for the most part, bullpen ERA did not correlate much with who actually was successful. Tampa was 7th, Toronto was 4th.
In 2012, this was more in line with Tampa, Oakland, Baltimore, leading the pack. Though once again Detroit 10th, Yanks 7th, Rangers 6th. Red Sox 4th in 2011 and so on.
On the other hand:
2013: The top 5 teams in Starters ERA: Detroit, Oakland, Tampa, Boston, Kansas City (with Cleveland, Texas taking next 2 spots)
2012: Tampa, Detroit, Oakland, Seattle, Anaheim (Yankees #6, Rangers #8)
2011: Tampa, Anaheim, Texas, Oakland, Yankees, Mariners, Tigers
Basically starter's ERA has been a much more durable predictor of playoff timber than bullpen ERA. I guess what I am saying is - we quibble about the Red Sox middle relief, but I'd temper it by noting:
1. Middle relief is the weak spot of EVERY bullpen, even the good ones
2. If we are getting into any bullpen early our chances to win go up
The Red Sox back of the bullpen is very strong, stronger than Detroit's ... if we are counting on 5th and 6th inning guys to win a postseason series, we have much bigger problems.