Attempting to Figure Out Boston Red Sox Pitcher Joe Kelly

The Boston Red Sox’s confounding power right-handed pitcher Joe Kelly is in his fourth season with the team. While boasting a stellar 2.12 ERA in 14 relief appearances, he is walking batters at a high rate and striking out even fewer. What’s the cause of this and what might his future hold? Let’s dig a little deeper to see if there are any answers.

After coming to Boston in a 2014 trade, Kelly worked exclusively as a starter until transitioning to the bullpen last year. The 28-year-old has long been lauded for his top-shelf stuff but the results, particularly with the Red Sox, have never matched. A great example of that was his 2015 season when he went 10-6 with a 4.82 ERA in 25 starts. It was perfectly acceptable stuff for a back-of-the rotation starter, but the former third round pick has long shown promise of more.

In his 17 innings this season (admittedly a small sample size), Kelly has permitted just 11 hits and four runs. However, he has walked nine while striking out just eight; an odd stat line for a pitcher who is one of the hardest throwers in the game. Indeed, the 98.7 MPH he has averaged on his fastball is the fastest of his career, and at least one stat service has him as the hardest thrower in the game this year. With such octane, one would think he would be fanning batters at a prodigious rate but a deeper look at the numbers show why he hasn’t.

It all starts with how frequently Kelly is utilizing his fastball. Strangely, he is throwing it just 56.2% of the time, which is by far the lowest mark of his career, and about 10% less than last year. For someone who threw the hardest pitch registered in Red Sox history earlier this year, the way he has increasingly abandoned the gas may seem inexplicable but it is paying off.

Kelly is coaxing an impressive 59.6% ground ball percentage on all balls put into play. This represents a career best (last year was 46.9%) and may be a combination of his heavy sinking fastball and batters waving at his darting slider.

Kelly’s slider, typically seen as his next best offering, is being thrown 27.2% of the time thus far—or almost double his previous career high. He still mixes in a curve (16.2%) but has all but given up on his changeup (0.3%). This combination of hard stuff with breaking balls has also led to career lows in line drive and fly ball percentages.

What is likely contributing to his lack of punch outs is his continued struggle to control his stuff. He has gone to a full count on a full quarter (17) of the 68 batters he has faced this season. He has surrendered eight walks and a base hit in such situations, representing a lion’s share of the damage he has permitted. He is throwing strikes just 59.3% of the time, which is well below his career rate of 61.3%.

It appears that even though he is in his sixth major league season Kelly is still figuring things out. His impressive ERA is reflective of a new approach and raw overall stuff. His control problems have prevented him from moving to the next level. Considering the strides he may still be able to make, especially when it comes to harnessing his arsenal, it’s easy to see why the Red Sox remain enamored with him. Time will only tell if he continues to put it together and blossom into the shutdown pitcher statistics suggest he is capable of becoming. In the meantime, he appears to be a different pitcher and is becoming a contributor, albeit one who can put people on the edge of their seats for the wrong reasons, for Boston, who desperately need whatever help they can get in their bullpen.

Statistics via FanGraphs and BaseballReference

********************************

You can check me out on Facebook or follow me on Twitter @historianandrew