After arriving in the 2013-2014 offseason in a big but low impact (at the time) trade, Brad Boxberger faced limited expectations. However, he soon emerged as one of the Rays bright spots in the otherwise dismal "all-in" 2014 season and was trusted by Joe Maddon with high leverage situations over more veteran pitchers, justifiably so with 14.5 K/9, 2.8 BB/9, and a FIP of 2.84. With Jake McGee expected to be on the DL until mid May, Boxberger stepped up and filled McGee's role admirably while he was gone. Although Kevin Cash had gone on record as saying he had no official closer, Boxberger obviously filled that role saving 13 games in 13 chances with a 1.10 ERA at the end of May 22.
The first signs of Boxberger's shakiness showed in a late May series against the Mariners. Back to back losses via homeruns at the time seemed to be minor hiccups in Boxberger's great season. However, an unsettling trend appeared as the normally reliable Boxberger racked up 2 blown saves and 4 losses from May 26 through July 7. Coupled with a 5.94 BB/9, 2.7 HR/9, and an extremely ugly FIP of 6.62; it seemed like Boxberger was having significant problems. The low point of Boxberger's season came when he gave up a walk off grand slam to 29 year old rookie, Paulo Orlando.
#Rays Boxberger said he saw on video that he was tipping pitches - especially changeup - and is confident he has it corrected— Marc Topkin (@TBTimes_Rays) July 8, 2015
As this tweet suggests, Boxberger likely sat down with Jim Hickey and examined his game film, discovering that he was tipping pitches. Being unable to pinpoint the exact point where he began to tip pitches, I used the May 26 cutoff date of Boxberger's first struggles to see if there was a difference in pitch outcomes.
From opening day to May 22, Boxberger threw his 4 seamer 56.58%, changeup 36.3%, and curve 7.12%. From May 26 until July 7, he threw his 4 seamer 55.09%, changeup 38.62%, and curve 6.29%. Throughout the entire season, his pitch tendencies have been relatively equal. The first red flag came when looking at whiff percentage.
From 4/1 to 5/22, Boxberger recorded a 4 seam whiff percentage of 15.72% and 17.65% for changeups. Out of 18 games, he was able to record a whiff percentage over 40% for a single pitch 7 times. Compared to only 2 games out of 19 from the period from 5/26 through 7/7, Boxberger was also only able to record a whiff percentage of 7.07% for fastballs and 11.63% for changeups.
The slugging percentage numbers against Boxberger are even more absurd. From 4/1 through 5/22, batters slugged .108 against the fastball and .389 against the changeup. From 5/26 through 7/7, they slugged .650 against the fastball and .423 against the changeup. Batters are putting up a slugging percentage against Boxberger's fastball similar to Albert Pujols in his prime!
While I am not a baseball expert, it does appear that there is evidence of Boxberger's pitch tipping. There has to be some reason for batters to go from barely making weak contact against his fastball to putting up MVP like numbers against it. Small sample size alert, but after discovering his tip pitching, Boxberger shut down the Astros in three consecutive days, finishing with 3 K's, 1 BB, 0 H, and 0 R in 3 IP. Hopefully the adjustments that Hickey and Boxberger have in mind allow him to get back on track.
All data collected from Brooks Baseball, Fangraphs, and Baseball-Reference.