Let’s take a look at the major changes in Hicks’ numbers. As I mentioned before he’s leading the AL in OBP. Due in part to the fact he is walking a lot more. Hicks has already walked 16 times this season (17.4%), way up from his career walk rate of (10.1%). Take a look at his plate discipline numbers (Below) and sure enough you see Aaron Hicks has flat out stopped swinging. Among players with 80 PAs, his O-Swing% is the lowest in the league, Z-Swing% is 23rd lowest, and overall Swing% is 3rd lowest in the league. His current O-Swing and Swing% would have been good for lowest in the majors last season as well, by a margin of over 2 percentage points apiece.

Plate Discipline

Hicks’ low swing rate is going to lead to a lot of walks. And walks are a good thing. His teammate, Brett Gardner, has made a career out of taking pitches. He currently has the lowest swing rate in the league and the second-lowest rate in the past three seasons combined. So does a low swing rate correlated to success at the plate? Below is a chart of last year’s qualified hitters OBP and TAv vs. both Swing% and O-Swing%, along with the correlation coefficient and p-value for O-Swing or Swing% significance as a linear predictor:

As you can see OBP and both O-Swing and Swing% are fairly well correlated and both serve as a very significant linear predictor of OBP as well (very low p-values). This is fairly intuitive. If a batter swings at balls less he is going to walk more, and get on base more. The relationship between TAv and both Swing% is less correlated but O-Swing% and Swing% serve as significant predictors. This one is also not hard to figure out. Generally, batters are not going to make good contact on balls out of the strike zone. The more balls out of the zone they lay off the quality of contact, and the higher TAv.

Swinging less isn’t always good however. Taking strike’s in the middle of the zone is not a good thing. Aaron Hicks, sure enough, has been guilty of this a lot this season:

He has only a 44.8% Swing% on pitches in the lower third of the strike zone and has only swung at 9 of 14 pitches over the middle of the plate!

Now this is a sign of regression to come for Hicks. Swinging at so few strikes is not good for power. I looked last year’s relationship between Swing% and ISO and the linear relationship was minimal, cor = 0.021 p-value = 0.805. If a hitter is swinging less overall, it does not tell you much about their power.

Hicks is not hitting the ball harder, he’s actually hitting the ball less hard. His Average Exit Velocity is 83.7 MPH down from 2016, (88.6 MPH) and below major league average, (87.0 MPH). Despite this Hicks is slugging at a very high rate. It is extremely unlikely for him to keep up this pace while he takes pitches middle-middle for strikes and makes relatively weak contact.

This does not mean that Hicks is destined for the bench once again. If he maintains his swing rates he is going to continue to get on base at a high rate. A solid outfielder with a plus arm and an 15% walk rate is likely an everyday quality major league player. However, a player with a 53% Z-Swing% is not going to slug .500. Aaron Hicks might be for real, just not the slugger he has been thus far.

However, it is not the high average for Headley that stands out to me. It is his new found power. Here are his career slugging percentages and isolated power, including this season:

Headley is currently slugging almost .500. He has barely touched .400 since 2012. Yes, the sample is extremely small but this sort of power is a far cry from what we have seen from him during his career in pinstripes. Even if Headley were to return to his 2016 form tomorrow, this hot start would be enough to significantly improve his power numbers on the year. His six doubles this season are already one-third of his 2016 total, 18. His WARP so far this season (1.2), is already comparable to his career high as a Yankee (1.6 in 2016).

What’s causing this power surge for Headley? One thing that stands out is his improved plate discipline so far. He has walked almost as much as he has struck out (14 BB, 19 SO). However, he seems to just be swinging less — not laying off balls. If you look at his plate discipline numbers (shown below) you can see that both his Z-Swing and O-Swing rate are down over 10 percent from last year. His Z-Contact rate is actually down slightly from last year. Swinging at fewer pitches certainly explains his elevated walk rate this year (14.4 percent in 2017, 9.6 percent in 2016). However, laying off more pitches in the strike zone and making contact at a very similar rate on those pitches does not explain the increase in power.

So is this all just a BABIP driven fluke? Possibly. But there are some other changes that suggest maybe the power is here to stay. Headley is putting the ball in the air a lot more this season. Here are his batted ball numbers from the past three seasons:

via Fangraphs

As you can see, he is hitting the ball on the ground less. His ground ball percentage is down and both his line drive and fly ball percentages are up on the season. When we look at his Statcast batted ball data it tells a similar story:

via baseballsavant

Although Headley is not hitting the ball any harder this year, his launch angle is up over a degree, after being almost identical the past two seasons. Here is a breakdown of his offensive numbers on batted balls. (A ball hit with a launch angle of 10-25 degrees is a line drive, fly balls are between 25 and 50, and pop ups have a launch angle of greater than 50):

via baseballsavant

This increase in launch angle has likely contributed to his success. When Headley puts the ball in the air he is significantly more productive. Even in his overall poor offensive seasons the last two years, Headley had a lot of success on line drives and fly balls. Headley did not need to get stronger or hit the ball harder in order increase his power. He has simply put the ball in the air at a higher rate this season and benefited from the success he was already having on line drives and fly balls.

Now, I am not claiming that Chase Headley is going to start slugging like Giancarlo Stanton. However, this is a man who did not have an extra base hit in April just one season ago. It does not take much in terms of power to make a major improvement. His on base numbers are certainly due to regress. By no means is Headley a .300 hitter — he is hitting for a very high average on ground balls that should regress towards his averages of the past few seasons. However, his success on batted balls in the air is for real. If he is able to maintain or even improve his current line drive and fly ball rate, Headley can be a decently productive hitter and turn what looked like a bad contract into a steal for the Yankees.

Lead photo: Kim Klement  / USA Today Sports