The Colorado Rockies have found some intriguing bullpen arms in September

The Colorado Rockies lost again on Tuesday night. It was a pretty typical road loss for them: score a few runs early, bats go silent, opposing team chips away and eventually overtakes them for the win. Nothing new here. More interesting than that, however, are the three bullpen arms that have emerged for the club heading into 2015 in Justin Miller, Scott Oberg, and Jairo Diaz. As Eric Garcia McKinley and I wrote earlier this season, the bullpen isn't the biggest problem the Rockies have, but that doesn't mean improvement in that area wouldn't be a good thing. Let's take a look at these three  guys and what they may be able to provide the Rockies going forward.

Justin Miller

Perhaps the most intriguing of this trio is Justin Miller. After putting up a 1.89 ERA and striking out over 10 batters per nine innings across 38 innings between Double-A and Triple-A this season, Miller joined the Rockies and did more of the same. In his 31⅔ innings with the Rockies in 2015, Miller has a 3.13 ERA and has struck out 10.8 batters per nine innings. All of his peripheral stats/ERA predictors -- pick your favorite out of FIP, xFIP, cFIP, SIERA, etc. -- think that he's actually been even better than his already good 3.13 ERA (69 ERA-) would suggest. If you narrow Miller's performance down to only his most recent sample, the games he's pitched in September, the numbers look even more impressive. In 12⅔ innings, Miller has allowed just one run (0.71 ERA) on only three hits and one walk while striking out 19. He's shown the ability to miss bats with both his fastball and his slider and after being a very under-the-radar minor league signing this past offseason, he could find himself pitching in the late innings for the Rockies in 2016.

Scott Oberg

Oberg is a bit more of a complicated case than Miller. After excelling at every level in the minors to the tune of an overall 2.10 ERA with 9.5 strikeouts per nine innings in 115⅔ innings, Oberg has struggled to make the transition to the big leagues in 2015. With a 5.02 ERA, 6.75 strikeouts per nine innings, and 4.4 walks per nine innings, Oberg's overall numbers in 2015 don't look pretty. On the bright side, he looks like he may have turned a bit of a corner recently. His last 12 appearances have been scoreless and he has struck out 8.71 hitters per nine innings. Unfortunately, Oberg's walks have also risen, as he's allowed 5.2 walks per nine innings during his scoreless streak, so it's entirely possible that this is all just a mirage. However, with a fastball that averages 95 mph and improving results, the Rockies would be wise to give him another shot in the bullpen next season.

Jairo Diaz

Rounding out the interesting trio is Jairo Diaz. After being acquired from the Los Angeles Angels in exchange for Josh Rutledge this past offseason, Diaz struggled for most of the year in Triple-A Albuquerque as he walked more than six batters per nine innings. Nevertheless, the Rockies were intrigued enough by his (on average) 97 mph fastball enough to call him up in late August anyway after a strong showing earlier in the month that saw him throw nine scoreless innings while striking out more than four batters for every walk. In his brief major league stint, Diaz has impressed to the tune of a 2.65 ERA in 17 innings of work. With just 6.9 strikeouts per nine innings, his peripheral numbers don't look quite as impressive as the raw ERA does. That being said, pitchers with the raw stuff Diaz has -- his slider averages about 90 mph -- tend to find ways to start missing bats as long as they can stay in the strike zone and work ahead in the count. As with a lot of young pitchers, that will be the challenge for Diaz. It's a challenge he's been adequate at so far with just 3.2 walks per nine innings, though his first pitch strike percentage of 55.9 entering Tuesday night leaves something to be desired; that number would put him 118th out of 137 qualified relievers in 2015. Diaz figures to be a primary piece in the 2016 Rockies bullpen and it will be fun to see how he does.

From now until the end of the 2016 season, the Rockies should be in evaluation mode. As weird as it is to say, it shouldn't necessarily be about the wins and losses right now, though of course wins are always nice. It should be about finding out which players can and can't help the club during their next contention window. It's still early -- the largest sample size we have from any of these pitchers is Oberg's 57⅓ innings -- but these are three arms to watch as the Rockies move forward.