The bullpen, like most areas of the team, was a weak spot for the Colorado Rockies in 2014. Two pitchers in particular killed the Rockies' efforts to keep games in hand between the time the starting pitchers usually exited the game and the back end of the relief unit took over.
Three pitchers in particular were extremely bad -- and in a fairly decent sample size -- when pitching to opponents in the fifth through seventh innings:
The sixth inning wasn't great, but the seventh inning? Absolutely atrocious. More than a third of the total batters in the seventh inning against the Rockies last season faced either Belisle, Brothers, or Masset, and the results of those plate appearances were most often somewhere between All-Star level and Hall of Fame worthy. It's no coincidence that the Rockies allowed sixth- and seventh-inning runs at a rate of nearly double the league average, per Baseball-Reference, and lost 23 games in which they were either ahead or tied entering the seventh frame.
The good news is that the front end of the bullpen has undergone a bit of a facelift, either by new acquisitions or shuffling of the incumbent staff, and should also benefit from help on the horizon.
Middle relief ace
Tommy Kahnle had a very good, very underrated rookie season after the Rockies selected him in the 2013 Rule 5 Draft. Things went off the rails a bit when the club began using him in later innings, but there was hardly a more dependable guy on the roster to bridge the gap than Kahnle.
Compare Kahnle's numbers to the guys in the table above (adding the fifth inning to illustrate his worth in the middle part of the game):
Kahnle struggled in the fourth inning and had his troubles in the eighth, but he could be counted on night in and night out to bail out the starters and give Colorado's setup man and closer the chance to come through in high-leverage situations. Now that Kahnle has been in the majors for a full year after being thrown into the fire, he should be expected to improve, especially in the area of strikeouts. His stuff is good enough to whiff more than a batter per inning, a figure he almost reached last season anyway. Perhaps he can become this year's Adam Ottavino.
David Hale was quite a bit better last season as a starter than a reliever, but the Rockies' rotation looks full after the signing of Kyle Kendrick. Colorado's Triple-A rotation is quickly filling up as well, making long relief Hale's most realistic role, at least to begin the year. The Rockies need a dependable arm there that can mop up a few innings at a time on occasion, and they could probably do worse than a grounder machine such as Hale.
Brooks Brown was death on right-handed pitchers after his call-up in 2014. Lefties didn't hit him particularly well, either, but Brown struck out 13 -- and walked only two -- of the 57 righties he faced. He's worth an extended look in 2015.
Say what you want about Christian Friedrich as a starter, but he seemed to find a niche in the Rockies' bullpen toward the end of last season. In 32 plate appearances, lefties hit just .138/.194/.207 with 11 strikeouts and only one walk against the 2008 first-round draft pick. Boone Logan prior to last season fared well in his career against lefties but couldn't get them -- or anyone else, really -- out in 2014. One positive note: Logan struck out batters at a rate of 11.5 per nine innings last season, repeating that figure from the year before. A little batted ball luck will go a long way for Logan this year, but he's going to need to stay healthy either way.
Let's talk about Rex Brothers for a second. He was awful last year; his delivery failed him, which affected his command to the point where his already high walk rate became astronomical. And, for the first time, Brothers was unable to rack up the strikeouts necessary to combat the abundance of free passes.
The good news is that Brothers is still young, and that when 2014 was all said and done, his peripherals weren't extremely different than the year before. Like Logan, Brothers will almost inevitably be better in 2015 simply as a result of better luck. The Rockies really need that, and if Brothers can provide it, their surprisingly deep bullpen will get a whole lot stronger.
Yohan Flande is still around and could provide some depth should something go wrong. New acquisitions Jairo Diaz (who could eventually be a closer) and Jorge Rondon have powerful arms and can miss bats. That's always a plus, especially at elevation.
Finally, let's not forget about John Axford, whom the Rockies signed on a minor league deal a couple of weeks ago. Axford, for all of his issues, can still strike hitters out with the best of them. If he can get some walk and home run issues ironed out, Axford could find himself closing games for Colorado this season while LaTroy Hawkins slides into a lower-leverage role that might be better suited for him.
On the farm
Ken Roberts, Scott Oberg, and Kraig Sitton aren't far away from contributing in the Rockies' bullpen. None of the three will light the world on fire, but Oberg has flashed good strikeout ability in his two full professional seasons and Roberts pitched well in the Arizona Fall League after a decent Double-A campaign.
Austin House is the most intriguing option of the minor league pitchers within spitting distance of the majors. House, who reached Triple-A last year but will likely begin 2015 in Double-A, has struck out a batter per inning during his minor league career and is yet another power relief arm picked up by Jeff Bridich for a minimal return during the offseason.