The Tampa Bay Rays claimed right-handed reliever Jumbo Diaz off waivers from the Cincinnati Reds on Friday, according to Mark Sheldon of MLB.com. Diaz, a 33-year-old righthander from the Dominican Republic that has earned his nickname, held opponents to a 3.14 ERA in 43 innings for the Reds last season. That’s pretty good! Unfortunately, Diaz is no longer a Red because his peripherals were bad. He walked 10.4 percent of the batters he faced, and gave up 1.67 home runs per nine innings. His strikeout rate dropped from a stellar 27.5 percent in 2015 to 20.3 percent last season, a below average clip for NL relievers. This resulted in a 5.24 FIP, the sixth-highest among NL relievers with at least 40 innings pitched.
In taking a flier on Diaz, the Rays are hoping they can cure what ailed him in 2016. According to Brooks Baseball, Diaz’s average four-seam fastball velocity was 96.9 miles per hour in 2016, down from 98.2 mph the season prior. His velocity trailed off as 2016 went on, dipping to just 96.4 mph in September. After swinging and missing on 18.2 percent of the four-seamers Diaz threw in 2015, opposing hitters whiffed on just 10.5 percent of Diaz’s heaters thrown last season.
One thing that may help Diaz’s chances of sticking on the 25-man roster is if he can pitch multiple innings in an outing. He did so in seven of his 45 appearances last season for a Reds bullpen that was the worst in baseball by just about every measure. He started to trust his slider more, throwing it a quarter of the time to all hitters and nearly twice as often to lefties as he did in 2015. He did so at the expense of his changeup, which has been the worst of his three pitches at the MLB level. He hasn’t shown a meaningful platoon split in his 138 MLB innings either, and limited left-handed hitters to a .295 wOBA last season (though that was largely aided by a .188 batting average on balls in play).
If Diaz can lower his walk rate back to 2015 levels, he could be a solid pick-up. His batted ball profile did not change all that much from 2015 to 2016, and the few adjustments — a slight uptick in ground ball rate, and the highest pop-up rate of his short career — were positive. Baseball Prospectus’ Deserved Run Average was high on Diaz as well; he sported a 3.55 DRA, which was actually better than the 4.18 DRA he managed in 2015.
Diaz is out of minor league options and currently pitching for the Dominican Republic in the World Baseball Classic. When he returns, he will contend for one of two or three potential spots in the Rays bullpen on Opening Day. Since Diaz is on the 40-man roster, he has a slight leg up on the likes of Tommy Hunter and David Carpenter, though Carpenter has impressed so far. Diaz may be able to edge out the struggling Danny Farquhar and Kevin Gadea for one of the final spots, but a host of younger relievers — Jaime Schultz and Ryne Stanek, among others — are also jockeying for position.