The Bullpen structure of the Braves has been pretty rigid. Kimbrel in the 9th. Venters in the 8th. O'Flahrety in the 7th. Unless there is an injury or an otherwise unseemly amount of use from those three pitchers, "O'Ventbrel" is the mantra of the Braves' bullpen use this year. It's hard to argue with the results -- the bullpen has been outstanding, easily leading in FIP and xFIP. However, there are obvious flaws in expecting to rely on these results to occur for the remaining 81 games, plus postseason play. The "7th Inning Guy", O'Flaherty, has pretty wide plantoon splits throughout his career. An outstanding .585 OPS against Lefty's, but a pedestrian .753 OPS against righty's. His splits this years are lower (.518/.660), but still significant. Either way, O'Flaherty his posting career best numbers in k/9, BB/9, and HR/9 which is good enough for a 1.24 ERA. As great as those numbers are, I don't expect them to stay at that level all season. Other relievers are over performing based on career rates too. I don't expect Sherrill, Linebrink, and Proctor to end up with their current ERAs of 2.61, 3.54, and 3.14, respectively. The Braves' starters only have the 15th most innings pitched. The bullpen has the 3rd highest pitched (behind only KC and BAL who are far from contention due to lackluster starting pitching). If they rely on their bullpen so much, they can't expect them to remain over performers for the entire season. The plan in the beginning of the year was to have O'Flaherty and Peter Moylan handle the 7th. Moylan and his very consistent ground ball rate would be a great asset as a talented right-hander to shore up the middle relief, which the Braves rely on as much as any team in baseball. Unfortunately, after back surgery the timetable to his return is uncertain. It just so happens the Braves have the next best thing in Cory Gearrin, who is inexplicably not on the roster.
If Gearrin were on the team, he should be used in the 7th most often if the frame had more right handers coming up. The problem with having bullpen use that is too rigid (like the Braves), is that it only gives opportunity to perform in certain situations, which may or may not occur. Gearrin and O'Flaherty should both be used in the 7th and should be used in an inning, whenever the the frame has more righty's or lefty's. You can use either of them in high leverage situations in extra innings (believe me, there's going to be plenty of those). If Gearrin and O'Flaherty have been over used, then Sherrill and Linebrink can pick up the slack. As of now, with the Braves relievers are over performing, it would be nice to have a righty with a proven track record to shore up the bullpen when regression candidates are plentiful. Our three best relievers right now are Venters, Kimbrel, and O'Flaherty. The bullpen would benefit if another adept righty were in the mix. Look no further than Cory Gearrin.
The reason he's not on the roster is apparently Scott Proctor. Signing Proctor to a big league contract was a mistake in the off season and a mistake now. He has a nice 3.14 ERA, but he has allowed .....46% of all inherited runners to score! It all adds up to a WPA of -0.3. Essentially, Proctor should be either released or demoted, to let Gearrin pitch in high leverage situations is capable of performing in. Let's say if the bases are loaded and there's two outs with a one run lead, I'd rather have Gearrin than Proctor.