One of the main story lines for the Diamondbacks 2016 season includes the statistical meltdown from left-hander Patrick Corbin. The Diamondbacks initially acquired Corbin at the 2010 trade deadline and Corbin debuted for the team in 2012. From 2012-2015, Corbin made 70 appearances with 65 of them being starts. Over that time, he went 26-21 with a 3.84 RA9 and 3.75 ERA over 400 1/3 IP. Last season, he pitched to a 3.60 ERA over 85 innings as he returned from Tommy John surgery. The solid performance last year gave everyone hopes that he would return to his pre-injury form, when he was an NL All-Star in 2013. It's safe to say that hasn't happened.
In 2016, Corbin has made 24 starts and it's been a disaster season for the 27-year old lefty. Corbin is 4-12 with a 5.58 ERA and more alarming a 6.94 RA9. The peripherals don't show any hopes for improvement, as Corbin has a 105/57 strikeout to walk ratio and Corbin has allowed 22 HR in 132 1/3 innings. At this point, everyone watching the team has waved their arms in disbelief as a young lefty continues to unravel with this season. Corbin has allowed the most runs in baseball this year with 102, with 20 of them being unearned. While the Diamondbacks defense has been laughably bad, no decent MLB pitcher should be giving up 20 unearned runs over the course of the season. The pitcher needs to sometimes pick up his own defense because even the best defenders will make errors from time to time.
So where has it turned south this year? One number that could explain the problem is a reduction in first pitch strike rate. In Corbin's breakout 2013, 70.2% of opposing hitters started the at-bat off with a strike. In 2015, Corbin's first pitch strike rate 61.3% and in 2016 it has dropped to 55.4%. With batters ahead in the count, that's allowed them to be more selective and aggressive towards Corbin's fastball as he's forced to throw it over the heart of the plate to get back in the count. The result is an 8% jump in hard-hit rate from 31.5% to 39.4%. The 8% comes from medium-hit balls becoming hard-hit. At the same time, his strikeout rate declined over 4% from 21.9% to 17.3% while his walk rate has jumped from 4.8% to 9.6%. That is a recipe for disaster for any pitcher on the mound.
Another incident I don't like is when Patrick Corbin threw his manager under the bus in a game against the Marlins on June 10th. At the time, Corbin was cruising through the game, as he allowed only 1 run through the front 6 innings of the game. In the 7th, Corbin allowed a leadoff double and Chip Hale immediately got 7th inning man Tyler Clippard warming. It wasn't a bad move on Hale's part because the team signed Clippard for innings such as that. Corbin apparently took offense to it and proceeded to walk two hitters that were batting below .200 at the time. After the walks, Hale did what any manager would do and asked his reliever to finish the inning. Things went south for the team as Clippard continued the meltdown with a Grand Slam and allowed 2 more runners to score to take the loss. After the game, Corbin threw his manager under the bus about him warming up Tyler Clippard. To me, that's a big no-no to do that no matter how terrible your manager is or how you didn't like getting pulled.
Going into that inning, Corbin had pitched 7 solid innings against the Cubs and 6 innings of 1 run ball. It seemed like Corbin was about to figure things out as he had lowered his season ERA to 4.48 and FIP to about 4.64. He was averaging 6 innings a start and a respectable strikeout to walk ratio of 51/21. After the game, Corbin has made 11 starts and is only averaging 5 innings a start with a strikeout to walk ratio of 53/34. The WHIP has also jumped from 1.30 before to 2.12 since. That isn't just walk rate that's going up, but also more hits allowed and hitters being more comfortable facing Corbin. That's resulted in a jump in ERA and RA9 to 6.71 and 9.39. Those numbers are completely unacceptable, considering Shelby Miller has been crucified by everyone with a 7.14 ERA and RA9.
So what does the team do with Corbin moving forward? They cannot continue to send out a pitcher that averages 1 run allowed per inning and expect to win for learn anything moving forward. However, the starting pitching depth has been stretched very thin this year. Rubby De La Rosa experienced a setback in his recovery from a minor UCL sprain and Tyler Wagner has been out since the middle of May with a lat strain that has not gone away and could sideline him for 10 months. Top prospects Archie Bradley and Braden Shipley are already in the big league rotation, both showing promise towards the future. That leaves only Zack Godley and Shelby Miller as possible choices to replace Corbin in the rotation. With Miller experiencing similar failures this year, that makes him a less viable candidate for now. Godley pitched 5 1/3 innings of relief, so he is stretched out if he has to make the start on August 17th.
From a long term perspective, there is little incentive to cut bait with Corbin. The entire pitching staff has experienced setbacks although we've seen flashes from Robbie Ray and Shipley to be in the rotation for the foreseeable future. The team has two problems with Miller and Corbin to fix in 2017, although I suspect that if they were to land elsewhere that the other team's coaches would fix their problems while the Diamondbacks get the shaft. In order to fix both players, they need to watch what went well for both pitchers and have them go with a similar approach. Although in Corbin's case, the problem is a sudden loss of command that seems to have occurred after his June 19th start against the Blue Jays, which was his last QS and win. Hopefully he is able to fix whatever is bothering him because the team needs him to help carrying the load in order to compete in 2017.