On Friday afternoon at Wrigley Field, with the Cardinals trailing the Cubs 3-2 heading to the seventh inning, Mike Matheny called on left-handed reliever Zach Duke to replace his starting pitcher Carlos Martinez. Duke turned around Ben Zobrist to bat right-handed, inducing a fly out to left field, before snaring a weak liner back toward the mound off the bat of Anthony Rizzo. With the right-handed hitting Willson Contreras due next, Duke was relieved by right-handed throwing Matt Bowman, who promptly recorded the third out. All told, Duke threw just six pitches, three for strikes.

On its own, Duke’s appearance doesn’t appear noteworthy. Nothing spectacular happened, and Duke has pitched in a lot of games. In fact, over the past three full major-league seasons, Duke was about as likely as anyone in the league to make an appearance on the mound in a game.

So what made Duke’s appearance special? To understand that, it’s necessary to begin with the fact that this was his first appearance in an MLB game in 2017. As the regular season ended last season in early October, the Cardinals reported that Duke had undergone Tommy John surgery while also having a flexor muscle repaired in this left arm.

Tommy John surgery has become something with which all baseball fans are familiar. At this point, it’s no longer shocking to hear that a pitcher has torn a UCL in his throwing elbow. By my calculations, over 26% of pitchers who appeared in an MLB game last season have had this type of procedure.

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The strike zone. Depending on your opinion of baseball’s home-plate umpires, you may prefer to call it “a” strike zone rather than “the” strike zone. You may not know what to expect on any given day while watching your favorite team.

Regardless of whether you think the calling of balls and strikes should be improved in some way, you at least have the option of knowing how the umpires’ collective zone appears objectively. For a decade now, every pitch thrown in the majors has been tracked. The position of every ball has been recorded as it crosses home plate. This extraordinary data has allowed for a quantitative assessment of what the strike zone looks like when aggregated over all pitches across the league.

During this era, the called strike zone has expanded rather significantly, in particular at the bottom of the zone. This trend finally ended last season, when both the overall size and lowest section of the strike zone actually shrunk ever so slightly compared to the 2015 season.

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It’s no secret that, over the last few years, the number of Tommy John surgeries has increased across all levels of baseball. As we emerge from the All-Star break, let’s take a snapshot of the current state of Tommy John surgeries at the professional ranks.

New Tommy John Surgeries
Let’s start with some good news. The number of Tommy John surgeries at the major-league level is down in 2016 compared with the last couple of seasons. Comparing totals at this point in the season over recent years, there have been fewer Tommy John surgeries to date this year than any since 2011.

In the past five seasons, I’ve attempted to track Tommy John surgeries at the minor-league level more closely than in prior years. This information is much more difficult to collect, and certainly there will be many surgeries missing from the list every season. Looking only at surgeries known to have been performed by this time in the year, however, the 2016 campaign looks more like 2012-2013 than the last two years where surgery counts had spiked.

So the most interesting question here is: has something actually changed to cause the number of Tommy John surgeries to drop this year compared with the last two seasons?

I can’t say that I know the answer, but I suspect it’s due to a number of factors.

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With strikeout rates soaring and run scoring dipping to generational lows in recent seasons, word came in the offseason that the Competition Committee would be monitoring the expanding strike zone in 2015. Given the scrutiny it is receiving at the league level, I have been tracking the strike zone over the course of the season, with updates at the end of each month. At the following links you can find the updates from the end of April, May and June.
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