Statcast: McCutchen, Hanley healthy, mashing

Trending exit velocity tells story of return to healthy form

Statcast: McCutchen, Hanley healthy, mashing

For years, we've regarded a change in a pitcher's velocity as something of a barometer of his health. If he's suddenly lost something on a fastball, it might be a warning sign that he could be hiding an injury. When a pitcher coming off an arm injury returns to his previous velocity levels, it gives confidence that his health concerns may be behind him.

So why can't we apply the same theory to hitters? It's something that's intuitively made sense -- if a hitter is working through an injury, he's probably not going to be able to turn on a ball like he normally would -- but we've never really been able to measure that effectively, at least beyond the eye test. Until now, anyway, because with Statcast™ we're able to do just that.

Cast your Esurance All-Star ballot for McCutchen and other #ASGWorthy players

Let's apply this idea to two of the most accomplished hitters in baseball over the last few years, Pittsburgh's Andrew McCutchen and Boston's Hanley Ramirez. Both players ranked among the top 15 hitters in baseball on a rate basis between 2012-14 (min. 1,500 plate appearances), and both tried their best earlier this season to play through a nagging injury that seemed to clearly limit their productivity.

McCutchen's struggles started immediately and lasted through all of April, which ended with a .194/.302/.333 line that qualified as the worst month of his entire career. From the outside looking in, the reason seemed clear -- McCutchen had been limited in spring training by a sore left knee, and even had to miss a game in early April to rest it.

While he insisted the knee wasn't the issue, it was hard to think that a month that poor could have come from anything else, considering McCutchen's established track record. Of the 186 hitters with 30 April plate appearances, McCutchen's average batted ball velocity was just 116th, at 87.79 mph. But near the end of the month, McCutchen told MLB.com that he wasn't worried, noting that "I'm feeling good, so the outcome will be there. Long as I feel good, I'll get good results."

It looks like he was on to something, as you can tell by his weekly exit velocity chart:

Week by week, McCutchen has been hitting the ball harder. We know that harder-hit balls are more likely to fall in for hits (or just leave the park entirely), and over the last 30 days, he's been hitting a much more McCutchen-like .340/.405/.515. Since May 1, he's jumped to 22nd in average velocity, at 92.62 mph. Whether the knee has improved or he's simply found a way to work around it, McCutchen has been consistently hitting the ball harder -- and results have followed.

Ramirez, conversely, sailed through his first month with Boston on a record-setting pace, tying David Ortiz's club record for April homers with 10 and leading all hitters with an average of 98.71 mph. But on May 4, he sprained his surgically-repaired left shoulder running into an outfield wall at Fenway Park, missing the next three days.

He avoided the disabled list, but the outstanding April (.293/.341/.659) disappeared into a disastrous May (.235/.286/.337). The MLB-best exit velocity turned into the 166th-best in May. But Ramirez has been much, much better in June (.308/.352/.462) and it's pretty hard to miss the trend his batted ball velocity shows:

Now, the eagle-eyed among you will certainly note that Ramirez's velocity was declining even before he injured his shoulder, and that's true, but that was always going to happen. That is, unless you think Ramirez was really going to continue on a 60-homer pace all season long, he was never going to maintain an average velocity of over 98 mph, not when only one hitter (Giancarlo Stanton, of course) is even over 95. The inevitable regression to the mean took some of Ramirez' velocity back; the shoulder, it appears took the majority of it. Now it seems that the shoulder is no longer an issue, and Ramirez's strength -- and production -- is back.

As you'd expect, neither spent time publicly blaming their issues on their health, and therefore neither is claiming that they're 100 percent healthy now. But from this angle, they don't really have to. The strength of the balls coming off their bats does all the talking for them.

Mike Petriello (@mike_petriello) is an analyst for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.