"I don't know what the future holds. I'm pursuing other things, but also trying to become a healthy human," Appel told Bleacher Report. "I'm 26, I have a Stanford degree, I have many interests beyond baseball, which I still love, but I have a lot of things I care about. I enjoy challenging my mind. My last four years in baseball have challenged my mind."

Appel, a right-handed pitcher who was selected first overall by the Houston Astros in the 2013 draft, told Bleacher Report that he hasn't ruled out returning to the game.

He was designated for assignment in November by the Philadelphia Phillies, who acquired him in 2015 in a multiplayer trade that sent closer Ken Giles to Houston.

Appel has dealt with injuries during his career and he did not pitch in the majors in five seasons at multiple levels. Overall, he is 24-18 with a 5.06 ERA in 375 1/3 innings pitched over 81 minor league games (78 starts).

Last season, he finished 5-4 with a 5.14 ERA in 84 innings.

"I'm a guy who loves a game, who had expectations, goals and dreams and then has had everything tumbling, and then everything was unmet," Appel told Bleacher Report. "Would I have loved to be pitching in the World Series? Absolutely. Some people have real struggles. I played baseball. I thought I was going to be great, and I wasn't."