The back end of the Rockies' bullpen was very quietly exceptional in 2012, with three of the six top NL relievers in rWAR calling Coors Field home.
The Rockies just concluded their worst season in franchise history (in case you had forgotten), but it could have been much, much worse. Standard were the games the Rockies lost in which the starting pitcher gave the club little to no chance to win. Often were the times the young and injury-riddled offense struggled to score runs on the road. Fortunately, it was fairly rare that Colorado took a lead late in a game only to lose it due to a shaky bullpen.
With the Rockies' piggyback system, Colorado obliterated even reasonable sabermetric ways to grade out a bullpen. Reliever WAR puts a premium on innings pitched, yet the designed early exits of the 75-pitch count led to a large innings load for Colorado, resulting in a 6.7 bullpen fWAR, tops in the National League, despite a 4.52 ERA. It also led to more appearances, which, in addition to a high offense environment, leads to more blown saves. Colorado led MLB in that department with 35, though only 7 were by Rafael Betancourt - the rest were really "blown holds").
If you break it down to look at the seven most prominant Rockies relievers though, Colorado routinely trotted out capable to dominant arms.
Rafael Betancourt continues to be one of the most underrated relievers in all of baseball. Despite a few hiccups in save situations, he was largely dominant, painting his low 90's fastball 75% of the time to get strikeouts without walking many.
Matt Belisle posted an ERA of 3.71, which appears to be the workload-led regression many came to expect, yet that was mostly BABIP driven. Thanks to a FIP below 3.00 and 80 innings of work, Belisle's fWAR rated him the 6th most valuable reliever in baseball.
Rex Brothers was one of the top 20 strikeouts specialists in all of baseball out of the bullpen, holding lefties to a paltry .206/.303/.284 line, striking them out more than 40% of the time. That ability to get out of jams ended up with him being credited with eight wins, more than any pitcher on the staff.
Josh Roenicke was a waiver wire pick-up in 2011, and all he did for the Rockies was lead all MLB relievers in innings with 88.2. He was effective over those innings too, with a 3.25 ERA. That run prevention combination led to Roenicke having 2.0 rWAR, ranking him 6th among relievers in the NL, behind only Aroldis Chapman, Craig Kimbrel, Rafael Betancourt, Matt Belisle and Wilton Lopez. Yet the Rockies tried to pass Roenicke through waivers, and the first team up on the waiver wire, the Minnesota Twins, snapped him up. After that season, why? I myself would not have exposed Roenicke as such, but he was certainly not as effective as he looked. His 54 strikeouts in 88.2 IP is mediocre at best, and the worst strikeout rate of his career. Roenicke also walked too many and inexplicably had a .276 BABIP against despite pitching at Coors Field and allowing an above average line drive rate. As tough as it may be to believe the MLB leader in innings hid in small sample size good fortune, that appears to be the case with Roenicke. He still would have held value going into 2013, but his loss won't be as large as it appears on the surface.
Adam Ottavino was a sly waivers pickup from the Cardinals, and after some time in AAA, became a crucial part of the big league bullpen. Ottavino carried an ERA below 2.00 for his first 18 appearances, then later became lynchpin in the piggybacker scheme. At the end of the year, Ottavino struck out more batters than innings pitched with a decent enough walk and groundball rate. His ERA may not be nearly as pretty as Roenicke, but he clearly is the more valuable reliever going forward.
Matt Reynolds burst on the scene at Coors Field as a rookie in 2010 with a 2.00 ERA and strong strikeout and walk numbers. He was even better to start 2011, posting a 0.34 FIP in April, but Reynolds has regressed since. Unable to thrive against left-handed batters and having an increasing problem with home runs (12.5% HR/FB in 2010, 16.4% in 2011, 20% in 2012), the Rockies decided to trade him to Arizona for 1B/3B Ryan Wheeler. Aside from home runs allowed (11), he pitched decently enough as a middle reliever. If he can get those in check (sorry about Chase Field, Matt), he'll be a decent reliever.
Carlos Torres was one of those minor league filler free agent acquisitions no one paid attention to in the offseason. He put together a sub-4.00 ERA in Colorado Springs and got his chances in the Rockies bullpen. In 11 appearances through the end of July, Torres had a 1.50 ERA, when he was cast as one of the chief piggybackers in the bullpen. His ERA suffered from the bullet-biting, but his 3.70 FIP in 53.0 IP was a significantly pleasant surprise. It wasn't to the level of protecting though, as Torres left as a free agent and signed as a minor league free agent with the Mets two weeks ago.
These seven all had flashes of brilliance and were well above average relievers by either rWAR or fWAR (except Reynolds). Yet it should be noted how they were acquired. There is one trade (Betancourt for Conner Graham), two draft picks (Brothers - supplemental 1st round, Reynolds - 20th), two waiver selections (Roenicke, Ottavino) and two minor league free agents (Belisle, Torres). For a midmarket team, it is certainly helpful to be able to identify cheap bullpen options.
Only four of these seven will return to the Rockies in 2013, but they are the most critical four - Betancourt, Belisle, Brothers and Ottavino. All four have shown an ability to pitch at Coors Field and fill critical roles (closer, set-up, lefty set-up and lefty specialist, middle long man). Colorado figures to have a solid bullpen in 2013 once again, once those back end roles are filled.