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Jason Heyward's loss of power and his approach at the plate

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Jason Heyward's power has gone down as he has spent more time in the leadoff spot. A change in approach might have caused the power drop, and a return to an aggressive approach could cause the power to return in 2015.

Justin K. Aller/Getty Images

Jason Heyward comes to St. Louis with a lot of positives. His defense is likely best in the league in right field. He gets on base, reaching more than 35% of the time. He is young, just 25 years old on a team with core players in their 30s. He is fast, twice stealing at least 20 bases. All of those attributes make Jason Heyward one of the best young players in best baseball, yet Heyward hit just eleven home runs last season. As Matt Carpenter showed in 2013, a player can hit eleven home runs and have an MVP caliber season, but if Heyward can find his powerstroke, the one that let him hit 27 homers in 2012, Heyward could have an MVP season in 2015.

The current narrative regarding Heyward's power drop relates to Heyward's approach. On the surface, the claim is an easy one to believe. As Heyward's plate appearances in the leadoff spot have risen, his strikeout rate and slugging percentage have fallen.

Leadoff PA K% SLG ISO
2012 0 23.3 0.479 0.210
2013 134 16.6 0.427 0.173
2014 428 15.1 0.384 0.113

This narrative (a narrative is not always a bad thing) has support from those close to the source. John Mozeliak forwarded the theory after the trade. Heyward did the same in this story from Derrick Goold.

"I do know a leadoff hitter is not one that's looked at to strike out a lot," Heyward said. "They're supposed to attempt to get on base every at-bat. Regardless of how it gets done, you're just trying to set the table. That was new to the season. I wasn't developed with that mindset."

Heyward is fudging the numbers a bit as his strikeout rate dropped in 2013, but his point is supported by the strikeout numbers. The more plate appearances he received at leadoff, the fewer strikeouts he made and the less thump his bat had in the lineup. The superficial analysis shows a fairly easily supportable theory.

If Jason Heyward were changing his approach, he might be pulling the ball less and hitting it to the opposite field more. here are those numbers of the last three years (data used to calculate numbers from Fangraphs).

Pull % Opp %
2012 29.8 16.5
2013 32.3 15.7
2014 29.4 19.2
Career 29.4 15.5

His pull numbers in 2014 matched his career average, although he did take the ball the opposite way more often in 2014. There is some evidence that pitchers are not pitching Heyward inside as often as they had. The problem in attempting to glean approach from these numbers is that they would also match up with someone who has simply lost power and for one reason or another cannot catch up to the baseball.

Heyward did fine against most fastballs in 2014. From Brooks Baseball, against fourseamers in 2014, he hit .268 with a .400 slugging percentage, not too far off from his career average of .268 and .418 against them. He fared poorly against sinkers in 2014, hitting just .276 with a .342 slugging percentage in only 123 at bats compared to career averages of .308 and .502. However, with such a small sample, it is difficult to draw any conclusions about the sinker given a lack of trouble against the harder fastball.

Yesterday, Joe took a look at the called strikes and balls for all Cardinals in 2014 using information from Baseball Savant. Using the same search function Joe used, Jason Heyward's numbers taking strikes are available. If Heyward is using a more patient approach as a prototypical leadoff hitter, he is likely swinging less and taking more called strikes, especially early in the count. The numbers below are for the first pitch in an at bat.

0-0 swings PA %
2012 148 651 22.7
2013 101 440 22.9
2014 135 649 20.8

Heyward is swinging at fewer first pitches, an indication he might have changed his approach slightly, but that does not indicate if he is seeing fewer strikes at which to swing.

0-0 taken strike PA %
2012 177 651 27.2
2013 138 440 31.4
2014 213 649 32.8

Not only is Heyward swinging less, he is taking more pitches for strikes. He swung at a slightly lower rate at first pitches from 2012-2013 compared to 2014, but he was letting a lot more hittable pitches go through the zone. Hitters in the majors last season hit .251/.314/.386, but after an 0-1 count, those numbers dropped to .221/.261/.331, conferring a considerable advantage on pitchers getting a first strike.

When Heyward gets the advantage of a 1-0 count, taking another pitch is a good way to get a pitch-count up and draw more walks, but Heyward could be letting hittable pitches go by.

1-0 swings PA %
2012 103 312 33
2013 52 199 26.1
2014 90 299 30.1

His swings were not appreciably different from prior years, but he again appears to take more strikes.

1-0 taken strike PA %
2012 89 312 28.5
2013 56 199 28.1
2014 95 299 31.8

The pitcher getting an advantage in an 0-1 count is not ideal, but going down 0-2 really hurts a hitter's chances of making an impact. After an 0-2 count, hitters hit just .166/.195/.242 in 2014. Here are Heyward's swings in 0-1 counts.

0-1 swings PA %
2012 133 283 47
2013 109 207 52.7
2014 127 283 44.9

Like above, swinging less is not necessarily a bad thing if the hitter is not getting strikes to hit.

0-1 taken strike PA %
2012 15 283 5.3
2013 10 207 4.8
2014 22 283 7.8

Heyward rarely lets a strike by in an 0-1 count, but he did do so slightly more frequently in 2014 than in previous years. Looking solely at the numbers is not going to determine whether Heyward changed his approach, but coupled with his own words, there is some evidence that he has. Here are his overall taken strike numbers, his swing percentages, and his contact rate when Heyward swings at a pitch in the strike zone. (First column from Baseball Savant, latter two from Fangraphs).

Overall Called K % Swing % Z-Contact %
2012 15.1 46.9 81.6
2013 15.6 44 84.8
2014 17.5 43.2 89.2

Heyward is swinging less and taking more strikes, information we likely knew was coming based on the information above. The third column is perhaps the most telling in terms of approach. When Heyward swings at a hittable pitch, he is more likely to make contact with it, but less likely to do damage. If this is an approach-based issue with Heyward purposely sacrificing power for contact and not related to how pitchers are pitching him or a decline in an ability to hit overall, then it is reasonable to think that Heyward's power can return in 2015 if he goes back to a more agressive approach.