A week has past since the Mets received the news that Matt Harvey’s season was over due to thoracic outlet syndrome surgery. For the rest of 2016 the Mets will have to figure out how to replace one of their "aces," but when 2017 rolls around what can the Mets expect from Matt Harvey? There were 14 cases of pitchers undergoing TOS surgery before 2016, 12 of which were starting pitchers.
Nick Lampe and Craig Edwards have done research regarding effectiveness and innings pitched before and after TOS surgery, coming to the conclusion that the procedure negatively affects a pitcher’s career and can sometimes end it (for example, Noah Lowry). How can past pitchers' experiences color the Mets' expectations from Matt Harvey moving forward? Using Edwards' list from his piece last week, let's try and forecast what can be expected of Matt Harvey when he returns using ERA-, FIP-, and fWAR. ERA- and FIP- are in terms of percentage points in the below table.
|Player||Year of Surgery||Age||IP Before||IP After||ERA- Diff.||FIP- Diff.||% Career fWAR Post TOS|
ERA- and FIP- are used because the aforementioned pitchers are from different eras in the game's history. In terms of ERA-, the average pitcher saw an increase of five percentage points relative to before TOS surgery. Harvey's career ERA- is 79, so an increase of five would put him at 84, which in 2016 lines him up with pitchers like Joe Ross, Zack Greinke, Bartolo Colon, Jimmy Nelson, and Martin Perez. As for FIP-, after TOS surgery, on average, pitchers were 10 percentage points worse. Currently Matt Harvey has a career FIP- of 71. An increase of 10 to 81 would put him in the same category as Aaron Sanchez and David Price.
The 2016 pitchers mentioned after increasing Harvey's ERA- and FIP- are certainly mid-to-top of the rotation starters in some cases. If Harvey returns in 2017 and pitches along the lines as Aaron Sanchez or Zack Greinke has in 2016, then I think the Mets would gladly take that. A post TOS Matt Harvey 2.97 ERA (Aaron Sanchez) or 3.62 ERA (Zack Greinke) would keep him on the career trajectory he was on before injuries started to derail him.
fWAR, like all of these measures, needs to be looked at in the context of the player's location on the aging curve at the time of the injury. Players like Chris Carpenter, Josh Beckett, Shaun Marcum, and Kenny Rogers were at advanced ages immediately before TOS surgery. Even though Rogers was 36 at the time of the surgery he wound up posting the most innings post TOS surgery, 1,253.1. Carpenter, Marcum and Beckett were at the end of their careers, but saw the end quickened due to TOS surgery. So far Matt Harvey has totaled a 12.1 RA9-WAR and according to the above model he has another 28.7% left to contribute in terms of RA9-WAR.
In order to gain a grasp on the control these pitchers had before and after TOS surgery, their walks per 9 gain give us a window into their control. Once again, in terms of BB/9 there has never been a pitcher with a lower BB/9 to undergo TOS surgery than Matt Harvey. The next closest to him is Chris Carpenter and Jaime Garcia, both with 2.6. Before his struggles this season Harvey had great control, which was what triggered concern this season was his lack of command at times along with a dip in his fastball velocity.
If there is one aspect of Harvey’s game that he has excelled in, it is his strikeouts. It is safe to say in order for Harvey to continue to succeed he will need to keep on his current career pace of 9.1 SO/9. Harvey has the lowest ERA, lowest BB/9, and now the highest SO/9 to undergo TOS. He is almost a full strikeout better than Josh Beckett, the closest to Harvey at 8.3.
There is no doubt the best pitcher to undergo this surgery is Matt Harvey. Statistically speaking, he has begun his career in a special way that has unfortunately been derailed by Tommy John surgery and now TOS surgery. As the Mets go into 2017 there will be concern about what the Mets can expect out of him in the future. If the data above above has shown us anything it is, generally speaking, the pitchers that return from TOS surgery pitch according to their career track, however there should be a significant concern with their durability. Considering the fact Matt Harvey is, in my opinion, the best pitcher to undergo this procedure, then there is little doubt in my mind he will return to form and build off his successful start to his career.