RP often have distorted numbers because of their short outings. If a RP throws 40 perfect innings but gives up a 3 run homer in the other 5 innings, his ERA is 3. Sprinkle in a run here and there during those 40 otherwise perfect innings and he's suddenly 4+. But, if you tell me my RP will throw 35 perfect innings, give up 1-2 runs in 5 innings and give up a 3 run dinger in the other 5, I'll take those 35 perfect outings, 5 meh outings and 5 complete crap appearances.