Last week, Steve Mancuso wrote an excellent piece about the Reds possibly pitching both Raisel Iglesias and Michael Lorenzen for 100+ innings as relievers. Bryan Price has used both semi-frequently for multiple innings at a time this year with great success. No one is surprised by this; Iglesias and Lorenzen possess great stuff, and in short spurts, that stuff plays up quite a bit.
This conversation has as much to do with the rotation as it does the bullpen. Starters pitch far more innings than relievers and have the difficulty of facing a lineup multiple times.