Matt Harvey’s slider could be key to his season

ESPN’s Adam Rubin posted an interesting story yesterday regarding Matt Harvey‘s potential performance in 2016. Specifically, he highlights manager Terry Collins‘ comments that Harvey has shown more spin on his slider and more late life on his fastball this spring than he had all of last season. If this is true, this is a very good sign for both Harvey and the Mets. Harvey’s slider at its best is one of the nastiest pitches in the game, and it’s exciting to hear that he’s getting back the effectiveness he had with it in 2013.

Is the improvement on his slider real or perceived, though? Perhaps this is just your typical manager-speak in Spring Training, along the lines of “in the best shape of my life” stories that typically litter the sports pages at this time of year. According to Rubin, Harvey threw his slider just 14.1 percent of the time last year, down from 18.5 percent in 2013 when his slider was lethal. This is roughly true, though the exact numbers vary depending on which data source you’re viewing. Rubin also notes that Harvey’s usage of the slider, which he wasn’t fully comfortable with until toward the end of the year, was concentrated more towards the last quarter of the season. That wasn’t necessarily true, at least according to the information in the table below from BrooksBaseball.net.

Still, the key to the discussion at hand is whether or not the slider itself took a dip in quality in 2015 when compared to 2013. There are various ways this can be analyzed, but we’ll stick to the spin rate and velocity of his slider in both 2013 and 2015 to see if there is any notable difference. Spin rate and velocity alone are not necessarily the most complete way to compare the quality of the slider (measurements like horizontal and vertical movement are important, for example), but they’re certainly important components that were highlighted specifically by Collins in Rubin’s article.

According to FanGraphs, the velocity on Harvey’s slider was 89.7 mph in 2013 and 89.4 mph in 2015. There was a drop, but not a very significant one. While a drop in velocity is an interesting data point, it’s not really all that surprising considering it was Harvey’s first season post-surgery. Collins mentioned “Tommy John hangover” as a reason that Harvey’s pitches may not have been as sharp.

Arguably the more interesting point here is the spin rate on said slider and if there was, in fact, a decrease in it from 2013 to 2015. During in the 2015 season, MLB Advanced Media added some additional advanced metrics to the leader boards at MLB.com. Those metrics, pulled from their proprietary Statcast system, included some samples of spin rate. The spin rate was immediately seized upon by the stat-crunching masses as potentially a new way to value pitches. A slider, for example, with more vertical movement is obviously not the same pitch as one at the same speed but with less movement. The same thinking can be applied to spin rate.

Unfortunately, it doesn’t look as if MLB has made all of that Statcast data easily available to the masses. Luckily for us, however, measurements like the spin rate of each pitch is recorded within MLB’s Gameday information for each game, which is readily available for those willing to parse the ugly data.

Using this data, we can gain insight into whether or not there was an actual difference in the spin rate of Harvey’s slider in 2015. The table below details the number of sliders thrown, his highest spin rate on a slider, his lowest spin rate, and the average spin rate for 2013 and 2015 regular season games. As you would imagine, the actual spin rate on each individual slider tends to vary widely. Note that spin rate is calculated in revolutions per minute (RPM).

Well, the numbers clearly show that Harvey actually did average less spin on his slider in 2015 than in 2013. His low was also higher in 2013, though his highest was higher in 2015. Terry Collins’ eyes did not deceive him, it seems. It’s interesting to note that he threw the slider over 100 times more often in 2013 than he did in 2015, despite starting three fewer games. Also note that his high in 2015 was an extreme outlier and occurred during the game against Cincinnati on September 26th. His next highest last season was 1573.94 RPM. In contrast, he threw the slider with an RPM of 1580 or higher 18 times in 2015.

Harvey also mentioned in the article that he didn’t feel good about the slider until about three quarters of the way into the season. Does the data reflect that? Well, through his August 11th start against Colorado, his slider averaged 605.10 RPM. From his August 16th start against the Pirates until the end of the season it averaged 832.37 RPM. So, he clearly did get a better feel for it towards the end of the season.

What does this all mean? Well, nothing until Harvey starts pitching in games and we can get data to back up what he and Collins are seeing and feeling. If his slider is back to its nasty 2013 level, though, Harvey really could be in for a very special kind of year.