The emergent stars in the Orioles bullpen, the best in the American League, have been Jim Johnson, establishing himself as an elite closer in 2012 and Pedro Strop as the setup man with the electric fastball.
However, they have not been the best duo in the Baltimore pen. That honor belongs to Darren O'Day and Troy Patton.
Patton and O'Day do not operate in the glamorous 8th and 9th innings, not typically anyway. They do not possess live fastballs that sit in the mid-90's or rack up saves. They just do all the dirty work and do it better than anyone else.
Some stats pulled from FanGraphs.com:
Name K/9 BB/9 K/BB HR/9 K% BB% WHIP ERA FIP E-F xFIP SIERA Darren O'Day 8.68 1.54 5.63 0.77 24.20% 4.30% 0.99 2.51 2.92 -0.42 3.51 2.90 Troy Patton 8.25 1.89 4.36 0.86 22.80% 5.20% 1.03 2.58 3.25 -0.67 3.33 2.89 Pedro Strop 7.14 4.35 1.64 0.17 19.80% 12.10% 1.1 1.22 3.38 -2.16 3.85 3.51 Jim Johnson 4.99 2.22 2.25 0.55 13.70% 6.10% 1.09 3.33 3.71 -0.38 3.79 3.18
O'Day and Patton lead Johnson and Strop, as well as the rest of the Oriole bullpen, in every major rate and fielding independent stat in the game. With fastballs that average about 85 mph and 89 mph, O'Day are 1st and 2nd in strikeout rate respectively. Their walk rates and WHIPs are lower, their K/BB rates are higher and their Fielding Independent stats, especially the ones that account for batted ball data, are superior.
Now, I have absolutely no issues with a tandem of late innings closers like Johnson and Strop who induce groundballs at rates higher than 65%. That probably helps to keep leads better than flyball pitchers like Patton and O'Day. But make no mistake, O'Day and Patton have been the better pitchers during the Orioles' improbably playoff chase this season.