The Red Sox played great baseball for most of September, but the way their last week went made it easy to have a sour taste in your mouth. I’m not at all confident that this stretch means anything, but it certainly would’ve been better if they had won more than one of their final six. In particular, the way their bullpen pitched in the last week was worrisome.

Craig Kimbrel had been dominant since coming back from the disabled list, but he totally lost his command in his last couple of outings. Additionally, Brad Ziegler, Koji Uehara, and Robbie Ross have all also shown some weaknesses of late. It’s not fair to let a few outings totally outweigh they did before that, but that it is the last thing we’ve seen does not bode well. At the same time, one pitcher is emerging to counteract these cold streaks. Against all odds, that pitcher is Joe Kelly.

Okay, it’s probably unfair for me to say “against all odds.” Converting the self-proclaimed future Cy Young winner into a relief role was hardly a novel concept. It’s something many have been calling for since shortly after he was acquired from the Cardinals.

I was certainly one of those claiming the move needed to be made, but I’m willing to admit I wasn’t as confident that it’d work as many. The way I looked at it, bad command is bad command regardless of how short your outings are. We’re still dealing with a small sample, and nothing definitive can be said about the transition thus far, but it’s fair to say Joe Kelly: Reliever is a success so far.

After being converted to the bullpen with Pawtucket in the middle of the season, he first emerged in Boston’s ‘pen at the end of July. He’s thrown 17-2/3 innings in the role, facing 69 batters. He has struck out 21 of those batters (30.4 percent) while walking just five (7.2 percent). Additionally, he limited those opponents to a .203/.261/.297 slash-line. In short, he’s been dominant.

Obviously, with the small sample size, we can’t take these numbers completely seriously. However, there is a tangible reason for different results — the change in role, of course — so there is some reason to believe Kelly is a new man. Unsurprisingly, a few things have changed since he made the move.

The first is the one that everyone hopes to see when a pitcher shifts from the rotation to the bullpen: The stuff is playing up. More specifically, he is throwing the fastball much harder right now. As a starter, Kelly was averaging a shade under 96 mph on the four-seamer. As a reliever, he is now a shade under 99. This is the dream scenario for those who believed strongly in this move.

Besides the velocity uptick, there has also been a change in repertoire since the shift. For all of the funny talk about him having five plus-pitches (thank you ESPN), the truth is he had a lot of pitches that weren’t very effective. The hope was that, as a reliever, he could focus on one or two more and really hone in on them.

Since moving to the bullpen, Kelly has abandoned his sinker, throwing just one according to Brooks Baseball. Now, he is leaning much more heavily on that hard four-seamer to go along with his breaking balls. He has one hard slider and a slower curve, which sit in the high- and low-80s, respectively. In fact, over the weekend Kelly showed off a new slider grip that helped him throw the pitch in the low-90s. If he can keep that up, watch out.

Ultimately, the question everyone wants to have the answer to is whether or not he can keep this up. Even if he can’t stay quite this dominant, Kelly continuing to be a trustworthy relief arm would be a huge step forward. I think it is worth noting what kind of offenses he has faced in this stretch. Since coming back up when rosters expanded in September, eight of his eleven appearances came against the A’s, Padres, Yankees or Rays. The first three of those teams were among the worst lineups in the second half, and the latter put up notable strikeout numbers all year. On the other hand, he did face off against the Blue Jays and Orioles in the other matchups and struck out eight batters in five innings.

It’s fair to wonder if he built this run on the back of bad lineups, but he has passed the eye test and pitched well in the opportunities he got against strong lineups.

In the end, I’m willing to admit that I’ll never fully trust Kelly. With the way he’s been pitching lately, that’s more of a me-problem than a him-problem. Still, he can’t be put ahead of Kimbrel, Uehara, or Ziegler in terms of right-handed relievers right now. What he can be, though, is a guy John Farrell can bring in early if a starter struggles and hope he can shut down a lineup in a multi-inning stint. It’s true that we are dealing with a small sample, and it’s possible Kelly’s transition has been a mirage. With the combination of strong numbers and tangible changes, I’m buying into this as much as I possibly can.