It wasn't supposed to be this way. Rex Brothers had just completed a dominant campaign in 2013, compiling a 1.74 ERA and striking out 10.2 hitters per nine innings over 67 1/3 innings - good for 3.1 rWAR and an insane 257 ERA+. Brothers was 26 years old and was a popular choice among Rockies fans to take over the closer role full time this season after earning 19 saves last year.
There were certainly warning signs among all that good news last year. Hitters against Brothers had a pretty low .280 batting average on balls in play while Brothers had a relatively high walk rate (4.8 BB/9) and his FIP (which looks primarily at things that defense has no control over) as a result was 3.49, nearly two points higher than his ERA. Some regression looked to be in order, but nobody expected this from Brothers in 2014.
While it was clear that Brothers wasn't the same dominant pitcher he had been the year before, the results for Brothers were actually passable (though still pretty bad) during most of the season's first half (4.38 ERA, 1.56 WHIP, .714 OPS against,). Still though, even when he was relatively successful, Brothers had already accumulated fourlosses and four blown saves (argh, should be called blown holds) in the season's first half.
Unfortunately, Brothers saw his season take a big turn for the worse after the All-Star break. In 17 1/3 dreadful innings (including more high leverage work than I would have liked to have seen), Brothers had a 8.31 ERA, 2.48 WHIP, and opponents had a 1.028 OPS against him. Even in a sample size as small as that one, every single one of those numbers is so abysmal that they can't be ignored.
Digging deeper into why Brothers had so many troubles in 2014 vs. 2013, we see that the lefty was less effective in pretty much every way. He walked more batters (1.4 more per 9 innings than 2013), struck out fewer (1.4 fewer per 9 innings), allowed more fly balls (10% more than 2013), and allowed more home runs on those flyballs (his 13.2% HR/FB number was 4% higher than 2013). Brothers struggled against both right-handers (.271/.366/.395) and left-handers (.309/.424/.485) - meaning that Walt Weiss wasn't really even able to use Brothers as a LOOGY with his struggles.
Brothers produced a 76 ERA+ season (24% worse than league average) a year after he was Colorado's best reliever. It's been reported that the Rockies tinkered with Brothers' mechanics before this year to avoid injuries down the road. If this is truly the case and the mechanical changes are somewhat to blame for the season Rex just had, then this is a pretty clear case of a player development failure at the major league level.
2014 grade: F
Overall, it was a nightmare season for Brothers just a year after he'd put together a dream campaign. It's a performance that leaves one of the bigger questions in a bullpen full of them entering this offseason.
What to expect in 2015
While his 4.53 FIP was more than a run lower than his ERA, Brothers numbers didn't exactly scream that he is a severe regression candidate, at least not back to the level of reliever he was in 2013. A 4.53 FIP reliever is nothing special, and Brothers seemed to only get worse as the year went on.
There was something that went very awry for Brothers this year, and whether it was changed mechanics, bad luck, or a sudden loss in pitching skill, it is pretty mysterious to the ouside observer how this happened. Furthermore, it's a bit of a mystery as to if 2015 will bring better results for Brothers. It's going to be a huge year for Brothers. who just missed Super Two arbitration eligibility this year and will make close to the major league minimum next year, both financially and in terms of proving that he is still a major league-caliber reliever.
It's no secret that Colorado's bullpen was historically awful in 2014 - and that Brothers was a big part in that awfulness. If a 2013 model of Brothers is present for the 2015 season (unlikely, but possible), that would go a long way towards overhauling the bullpen. As it is though, it's hard to count on Brothers for much of anything in 2015.