Barring any setbacks, Zack Wheeler will rejoin the Mets' rotation sometime around the 2016 All Star Break, giving a star-studded rotation yet another potential ace. Wheeler probably wanted to be on the mound sooner than that, but management pushed the 15-month Tommy John recovery timeline used by Matt Harvey and slowed Wheeler down. This means we'll only get a half-season glimpse of the potentially-historic homegrown Mets rotation, but "Big Sexy" Bartolo Colon will be a fine fill-in until then.
With the continuous pipeline of aces the Mets' farm system has produced recently, it's easy to forget that Wheeler was ranked higher than any other Mets pitcher before his debut, checking in at fifth on the 2013 Baseball Prospectus top 101. It's also easy to forget that in 2014, Wheeler was one of only four qualified starting pitchers to strike out more than a batter per inning and record a ground ball rate of more than 50 percent. The other three were Francisco Liriano, Felix Hernandez, and Clayton Kershaw. In terms of raw stuff, Wheeler might be the best of the Mets' crop of young arms, and when he's on, he can deliver gems like this one:
The issue with Wheeler has always been his control, or his lack thereof. In 285.1 major league innings, Wheeler's BB/9 sits at 3.94, and he averages only 5.1 innings per start thanks to the his elevated pitch counts. Wheeler's surgery could be cause for optimism in this area, however.
In an interview late in 2015, he mentioned that he's pitching pain free for the first time since high school. This long term pain can be explained by the torn tendon and calcification found in Wheeler's elbow during his Tommy John surgery. With those issues cleaned up, it's not unreasonable to expect that Wheeler will have more success controlling his pitches. The improvement might not be immediate, as control is usually the last thing to return after Tommy John, but there's reason to expect long-term improvement.
Wheeler's total 2016 impact will likely be small. He'll have limited time to regain his command in half a season, and he'll probably get pushed to a late-inning relief role come playoff time. Regardless, the tantalizing upside, both for Wheeler individually and for the Mets' rotation as a whole, should be great fun to watch in the second half.