Colorado Rockies: What Will Jairo Diaz Bring to the Bullpen?

Unless you’re a hardcore Colorado Rockies fan, you’re probably not familiar with the name Jairo Diaz. But now almost a year after tearing his UCL, the talented right-hander is closing in on a return, and could have a big impact in Colorado’s bullpen.

In December of 2014, the Rockies acquired Diaz from the Los Angeles Angels in exchange for Josh Rutledge. The trade generated very little fanfare. If anything, it was only notable at the time because it signified that Colorado was committing to DJ LeMahieu at second base.

Diaz entered the Angels system as a catcher, but after two years of struggling to hit at the lowest levels of the minors, he was converted into a relief pitcher. Diaz wasn’t an instant success, but armed with a fastball that could reach 100 MPH, he eventually worked his way through the ranks of the minors, going all the way from High-A to MLB in 2014.

The Rockies put Diaz in Triple-A for most of 2015 before calling him up near the end of August. Diaz pitched 19 innings at the MLB level and looked excellent, posting a 2.37 ERA and 18 strikeouts. Last offseason, there was talk that Diaz could be a major piece in Colorado’s bullpen, and perhaps even close some games while Adam Ottavino recovered from Tommy John surgery.

Instead, Diaz suffered the same fate as Ottavino, tearing the UCL in his right elbow early in Spring Training. In a moment, the season that looked like it would be his first full year in the majors turned into a full year of rehab for Diaz.

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As Diaz began the long process of working his way back, attention shifted towards other young, promising arms in the Rockies system. Players like Carlos Estevez and Miguel Castro, not to mention the return of Ottavino, turned Diaz into an afterthought once again.

Last month, the Rockies quietly activated Diaz off the DL and started him on a throwing regimen at the team’s facilities in the Dominican Republic. Obviously, there’s a big difference between throwing on a back mound at the team facility and pitching to MLB hitters. But if Diaz was throwing a baseball under team approval, it likely means his recovery is going well.

That’s the last news update we’ve heard on Diaz, but in this situation, no news likely means good news for both Diaz and the Rockies. According to reports, Diaz is resting this month before reporting to Scottsdale for his pre-spring throwing program. With Opening Day still over three months away, it’s not crazy to think Diaz could be ready when the season starts.

No one knows for sure how Diaz will look when he returns. Tommy John is a major operation, and there are no guarantees that Diaz’s fastball will still have the same explosive velocity post-surgery.

Even a minor velocity dip can be a major problem for a relief pitcher. In MLB, a 98 MPH fastball is special, a 94 MPH fastball is not. If Diaz doesn’t return to his old maximum velocity, it may be difficult, if not impossible, to live up to his potential for dominance.

Diaz has also struggled to throw strikes consistently so far in his young career. In 74 combined Triple-A and MLB innings with Colorado in 2015, Diaz walked 43 batters. That’s a 5.23 BB/9 ratio, far too high for a pitcher who wants to sustain any real success in the big leagues.

Of course, Diaz has fewer than 500 innings under his belt as a pitcher, so it’s not surprising that he would struggle to control the strike zone at times. At just 25 years old, Diaz is still younger than than Rockies starters Tyler Chatwood and Tyler Anderson. Elite, or at least acceptable, control is one of the last things to develop in most pitchers, and there’s still plenty of time for Diaz to find it.

There’s a chance that Diaz will not have the same explosive stuff post-surgery, but at the moment, there are no huge red flags indicating a full recovery will be extraordinarily difficult for him. As previously mentioned, Diaz is young and, outside of this surgery, he’s had a mostly clean bill of health. There’s no such thing as a routine recovery from Tommy John surgery, but Diaz’s chances of bouncing back seem as good as anyone.

Even if the fastball that flirts with 100 MPH is gone, that’s not necessarily a death sentence for his career. A drop in velocity can be a problem, but it can also force a pitcher to learn how to use other tricks, like movement and varying speeds. A 98 MPH fastball is hard to hit, but a 95 MPH fastball with sink or cut might be even harder.

In all likelihood, Diaz will start 2017 in Triple-A. By the time Opening Day rolls around, it will have been over a year and a half since Diaz pitched in a game that counts. The Rockies bullpen is far from settled though, and if Diaz returns and looks sharp in Spring Training, he could force the team’s hand.

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Even if Diaz leaves Spring Training and reports to the Isotopes instead of the Rockies, there’s still a good chance we’ll see him in the big leagues at some point in 2017. Remember, this is a guy that was seemingly in line for a big role heading into the start of last season, and the bullpen doesn’t look any better on paper now than it did then.

We may not know much about Jairo Diaz right now, but if things break right this season, we’ll be hearing a lot more about him … and soon.