(Kevin C. Cox/Getty Images)

For all of his considerable talent and ability — an .834 OPS and two all-star appearances before the age of 21 — Bryce Harper is still learning. He has shown an aptitude to adjust and an understanding of the strike zone beyond his years. But Harper still has one particular area in need of improvement: his ability to hit left-handed pitching.

Harper’s first true taste of specialized left-handed pitchers came in professional baseball. In 2012, after a torrid start and then a summer lull, Harper finished with a  respectable (for a rookie) .240/.300/.415 triple slash line against southpaws.

But in an injury-plagued 2013 season, he regressed. Playing hurt certainly played a major factor but at times he looked lost against left-handers and produced a .214/.327/.321 slash line against them. At one point in July he was hitting around .163 against left-handed pitching, and on July 4, the Brewers intentionally walked Ian Desmond to load the bases in order to have lefty Tom Gorzelanny face Harper. He grounded out.

So we asked our resident Pitchf/x expert, Harry Pavlidis, to take a deeper look at Harper’s season against left-handed pitchers. They attacked Harper as expected, firing hard stuff inside — fastballs and sinkers — and then getting him to chase breaking pitches away. What Harry found was less about opposing left-handers exploiting the low and away corner of the strike zone but more about the type of pitches used against Harper and how he handled them.

First, let’s establish the baseline. Hard stuff is defined as fastballs, sinkers and cutters, while soft stuff is curveballs, sliders, split-fingers and change-ups. Harper hit hard stuff from left-handed pitchers far better than the average left-handed hitter. But against soft stuff, Harper was noticeably worse than average.

Harper and MLB average vs. hard and soft pitches from left-handed pitchers in 2013

  Average On-base percentage Slugging
MLB average .254 .326 .375
Harper .306 .436 .472
MLB average .193 .233 .299
Harper .100 .182 .133

After returning in July after a month away because of his left knee injury, pitchers would flick soft or breaking stuff up at Harper and he would chase the pitches away. They would start with a change-up or slider on the outer half, which is doubly difficult because it breaks away from Harper, and each subsequent pitch was farther off the plate. Holding off on swinging at these pitches comes down to pitch recognition and strike zone awareness. On occasion, Harper would bite the jersey over his right shoulder, a way to remind him to keep his front shoulder square to the pitcher longer, which allows him to harness the power in his swing and allow him reach outside pitches better.

Harper’s slugging percentage against soft stuff from left-handers last season was even lower than his on-base percentage. And Nationals hitting coach Rick Schu believes Harper’s struggles ultimately came down to injuries. Schu admits he isn’t a “big stats guy” so he didn’t need to hear all of the breakdown in statistics to offer his thoughts. He felt that Harper’s injuries to his lower body — hip and knee — were preventing him from driving pitches and messing up his timing.

“There are some tough lefties in our division,” said Schu, who was promoted to the big league job in July and has worked with Harper since he was drafted. “But when he’s 100 percent, his confidence level is so much better and he doesn’t have to cheat with his lower half and doesn’t have to cheat on his fastball and then miss the offspeed.”

Throughout the season, however, opposing left-handers noticed something in Harper and began shifting how they attacked him. As the season progressed, they began throwing more hard stuff at him.

Left-handed pitchers’ mix vs. Harper in 2013

Month Hard Soft
April 51% 49%
May 47% 53%
July 56% 44%
August 66% 34%
September 66% 34%

Why? A look at how Harper fared against those hard pitches month-by-month reveals some possibilities. Before he first hit a wall on April 30 in Atlanta, Harper was hitting like an MVP candidate: .344/.430/.720 with nine home runs. Then, he smashed into the wall in Los Angeles on May 13 and played hurt for the rest of the season. So, in those first two months, even injured, Harper crushed hard stuff from left-handed pitchers. Then, his knee injury was aggravated on May 26 and he landed on the disabled list and opposing left-handers adjusted.

When he returned, they attacked him with more hard stuff. Maybe opponents were trying to exploit his timing after a month away on the disabled list. Or, they were trying to see how Harper and his lower body would respond to those hard pitches; testing his injury. It worked.

As evidenced by the chart below, Harper’s slugging percentage against hard stuff from left-handers dipped to .333 in July and .368 in August. In those two months, Harper hit .269/.368/.462 with seven home runs. None of those home runs, however, were against left-handers. Overall, only two of his 20 home runs in 2013 were off left-handed pitching, compared to six in 2012.

In September, and even as he battled the hip discomfort, Harper adjusted to the left-handers’ hard stuff and posted a .467 slugging percentage. One month isn’t much of a sample size — he notably doubled off all-star left-handed starter Patrick Corbin on Sept. 27 — but it was an encouraging sign for the Nationals that Harper was improving.

“If anything, he tried to cheat a little bit and he’d get out and not trusting it and getting banged up a little bit,” Schu said. “When he’s healthy, he’s great. It’s also a matter of (pitch) recognition. I’m not worried about him hitting lefties.”

Harper’s slugging percentage vs. hard pitches from left-handed pitchers in 2013

Month Slugging percentage
April .667
May .615
July .333
August .368
September .467

While Davey Johnson sat other left-handed batters against left-handed pitchers at times during the season, he often kept Harper in the lineup because he wanted him to continue to learn. He tried spacing out Denard Span, Adam LaRoche and Harper in the lineup, but still opposing managers brought in left-handers solely to face Harper in crucial spots. “Harp, he’s the marked guy,” Schu said. “He’s like Barry Bonds in that way. They’re focused in him, whether it’s a lefty or righty.”

Because of his talent, the Nationals expect Harper to handle left-handed pitching. They believe he can overcome his lack of success against left-handers in 2013. And there’s reason to believe it can happen based on what Harper accomplished against left-handers in 2012.

“As far as I’m concerned with Bryce, there’s no fear,” Schu said. “He’s not afraid to face lefties. But overall, just being healthy. More than anything, he just needs to get healthy and get that lower half 100 percent. He’s just such a leverage guy and I think a lot of his power and swing and confidence that’s all coming from being healthy.”

And there is something to be said about a player’s confidence. “When his confidence is going, it doesn’t matter who you are on the mound,” Schu said. “It slows the game down for him. He’s hitting everything. He’s a freak.”

In order to achieve that, Schu believes an uninhibited Harper will be able to better attack left-handed pitching. Harper had the bursa sac in his left knee debrided and cleaned up in late October and recently began his rehab.

“I’m very excited that he got his knee fixed and he can come back ready for next season,” Schu said. “I would like to see him hit less [in the offseason], rest and get healthy. Obviously, he couldn’t hit right after the surgery. But I want him to get healthy. “