1. Rangers (#26 in bullpen ERA in 2011)
1. Orioles (#27)
2. Yankees (#4)
3. A's (#18)
4. Pirates (#20)
This is bad news for every team in the AL except the Rangers, because their bullpen was their biggest weakness last year (when they still came within a strike of winning the World Series).
The Orioles (who have ranked near the bottom in bullpen ERA for the last decade) have almost completely revamped their bullpen and it is working so far. They've had a nice run lately, winning 4 in a row (allowing only 5 runs in the process). It seems likely that the O's will eventually be overwhelmed by all of the talent in the AL East, but they're holding their own for the time being.
The Yankees need their bullpen to be this good because their starting rotation is ranked 28th, and they just lost Michael Pineda for the season.
It looks like Pittsburgh may need the best pitching in the league (they're currently #2) to avoid losing 100 games, because they are dead last in runs scored by a wide margin. Oakland is in basically the same boat, except they're 28th in runs instead of 30th.