The home run derby isn’t for another month — July 13, to be exact, in Cincinnati — and Bryce Harper hasn’t been selected to an all-star team — the teams aren’t announced until early July, but Harper already isn’t sure if he will compete in the hitting contest. The biggest reason is personal: his father, Ron, who threw to Harper during the 2013 home run derby, underwent rotator cuff surgery after a winter snowboarding accident.

Harper, by some measures the best hitter in baseball so far this season, leads the National League in all-star voting (2.3 million votes) and the majors in home runs (19). But if he is selected, Harper isn’t sure if he will participate because he of his dad’s injury. Ron is still in a sling and may not be able to throw for many more months.

“We’ll see,” Harper said. “I’m either gonna do it or I’m not. It’s not ruled out, but am I comfortable doing it without him? Not really. If I decide to do it, I’ll pick somebody.”

Harper considers his father a best friend and he has been his baseball coach and batting practice pitcher much of his life. When Harper was a little kid, he told his dad that if he was ever in a home run derby that he wanted him throwing to him. The two got to live out that dream in 2013. Harper put on a show that night but finished second to Yoenis Cespedes.

“If I win it for the first time, I want it to be with my dad,” Harper said. “That’s something really special. We’ll see. I’ve still gotta make the all-star team.”

There is, however, another deeper reason Harper is leery of home derby competitions and it has to do with the idea of hitting home runs on demand.

“I haven’t taken BP all year outside,” Harper said. “It’s so tiring. I don’t think people understand how tiring it gets after four or five rounds. It’s tough.”

In spring training, Harper decided to try something new by not hitting on the field during batting practice. He felt himself getting tired after several all-out rounds of batting practice and only took swings in the indoor batting cages. In early April, he decided to try on-field BP again. “I was lagging by game time,” Harper said.

So Harper talked to Nationals Manager Matt Williams and hitting coach Rick Schu, who both were fine with Harper hitting solely in the indoor batting cages before games. Since the second half of 2013, Denard Span has done the same, too. “It felt good so I stuck with the same thing since,” Harper said.

The idea behind hitting only in the batting cages makes sense. On the field, players try to hit the ball hard and far. In the cages, Harper doesn’t see where the ball goes and he can focus solely on making contact, his positioning and swings.

“It’s more about staying on the ball,” Harper said. “Not knowing where the ball is going. Once it hits the side of the cage or back of the cage, it’s gone.”

Harper can also focus on situational hitting. During batting practice, Ali Modami, one of the Nationals’ batting practice throwers and a left-hander, shouts out scenarios for Harper — runners on first and second with no outs, first and third with the infield in — and Harper focuses on hitting the ball in that situation. “A home run works in every situation,” Harper said.

Because on-field hitting can be so taxing, Harper is also trying his best to conserve himself for the entire season. Because of a knee injury in 2013 and a thumb injury last season, Harper has logged only 19 games combined in May and June the past two years.

“I’ve never played in May or June,” Harper said. “I’m just trying to stick with my same routine and do what I need to do. When I get into BP, what’s the point of BP? Trying to hit homers for the fans. That’s what BP is. It’s about hitting homers and showing off. I don’t need to show off. I don’t need to hit homers then. I can do that in a game.”