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Kevin Kelly: The Sweeper Master

The reliever shared his thoughts with us.

MLB: Game Two-Tampa Bay Rays at Kansas City Royals Peter Aiken-USA TODAY Sports

St. Petersburg, FL: The sweeper master AKA Kevin Kelly has been one of the best rookie relievers in all of baseball.

Kelly was acquired last December, and in Spring Training he earned the last bullpen spot. The Rays always loved his arm slot, which gives opponents a very unique perspective, but he is finally putting it all together. What’s he doing right? He shared his perspective in a recent interview.

Missing Barrels

Kevin Kelly is finding success by taking away something hitters love, barrels! Kelly ranks in the 98th percentile at missing barrels; actually, opponents hitters only barrel the ball 2.4% of the time (the MLB average is 7%). How does he do it? Well, Kevin Kelly gives a brief explanation of how he works to make hitters uncomfortable.

I guess most of the pitches that I throw like the sinker and slider are kind of just the standard to miss barrels with it. But, not get swing and miss on it, which I think probably helps the barrel rate. So, I give up a lot of contact and some luck is involved. Small sample but yeah, probably just moves a bit.

Ground Ball Hunter

One of the most common routes to success from pitchers is the ground ball; that is something that Kevin Kelly has been able to execute as time has gone by.

The following graph will show Kelly’s progress with ground balls.

Kevin Kelly Ground Ball%

Month Ground Ball %
Month Ground Ball %
March/April 44%
May 45.90%
June 52.20%
July 62.50%
Fan Graphs

One of the main reasons Kevin has been able to increase the GB% is his sinker; it doesn’t rank at the top in vertical or, horizontal movement, however, the location is the main characteristic.

I definitely try to pitch for ground balls especially against righties when with my sinker. So, most of that’s just location trying to be down and in on guys, and trying to get them to roll up or something.

Kelly usually prioritizes location over movement. He is able to locate the sinker down and in against righties to produce multiple ground balls; that’s the reason why the results more often than not are positive.

The following image highlights where Kelly locates the sinker against RHB. The image shows everyone why he gets plenty of ground balls.

Pitch Mix

Kelly is rare among today’s relievers in that he doesn’t overpower the opposition. He works from east to west, being very cautious with location. Kelly throws a sinker (46%), sweeper (41.6%), cutter (11.7%), and in some spots, he throws a 4-seam fastball (0.7%).

The majority of Kelly’s success comes from his main pitches, the sinker and sweeper. Both avoid hard contact (37.7%) and generate good (for the defense) launch angles (-3). In other words, the ideal formula to avoid base hits. The sinker has amazing results with a .277 wOBA (MLB average .310) with a .301 xwOBA.

With the sweeper Kelly uses the same formula all over again; weak contact (hard hit% 18) and poor launch angle (26). Moreover, the results excel in every category; the wOBA.196 stands at and, the xwOBA results in .221.

Cutter Usage

The cutter is Kelly’s third pitch; he uses it around 12% of the time, but increases to 26% when facing lefties. Next, Kelly gives us a brief explanation on why he uses the cutter against lefties.

It just gives another option just that batters need to think about it. Because lefties generally do better against sinkers. So, just another firm offering that they have to deal with. I don’t know if I technically have the best results on it, but I think it makes my slider and sinker play up to them; like giving them another option.

As he said the cutter doesn’t have the best results; it has a .466 wOBA and a .450 xwOBA. However, as he said he gives batters another pitch to worry so his quality stuff is not too hittable.

Kevin Kelly has been one of the best dark horse stories, and he has responded with great professionalism. He has gone from low-leverage situations to one of Cash’s most trusted arms coming out of the pen. Here is what Kelly said about using a mindset to face high-leverage situations.

I’m definitely more used to it than ever. I think the important thing is remembering that getting ahead, gets you outs. So, you can nibble even if it’s a big situation just remembering that.

Kelly has had an incredible run with only 3 runs allowed since May 12. Those 3 runs came in the same game when Corey Seager smashed a three-run homer off Kelly. Other than that he has helped in so many different ways, from getting the 3 big outs, or mound getting 6 to 9 outs in long relief. Kelly explains what has been key in his outstanding run.

I think I’ve been getting ahead a lot better, like in 1-1 counts, getting strikes there. Being able to get good counts has helped a lot. Also, making guys go down-swinging with pitches out of the zone and stuff like that. There’s obviously some luck involved too; like balls not going through and we have a good defense behind me all the time. So, there’s definitely some of that, mostly I think getting ahead and having some better luck.