HOUSTON -- The moment has played out in the mind of Astros top pitching prospect Forrest Whitley repeatedly for quite some time. He smiles at the thought of it, knowing it's closer in 2019 than ever before. The big leagues are looming, and Whitley has done everything in his power

HOUSTON -- The moment has played out in the mind of Astros top pitching prospect Forrest Whitley repeatedly for quite some time. He smiles at the thought of it, knowing it's closer in 2019 than ever before. The big leagues are looming, and Whitley has done everything in his power to put himself in position to seize the opportunity.

Coming off what amounted to almost a lost season that began with a suspension and ended with an injury, Whitley dominated in the Arizona Fall League and has tweaked his mechanics and his body -- putting on 30 pounds from last spring -- in anticipation of the biggest year of his young career.

Astros president of baseball operations and general manager Jeff Luhnow has said more than once he expects Whitley, a 6-foot-7 right-hander taken in the first round of the 2016 Draft and the No. 8 prospect in baseball as determined by MLB Pipeline, to make his big league debut at some point this year.

"I've played it over in my head quite a few times, so that's going to be a very special day for me and my family, and hopefully it happens sooner than later," Whitley said Thursday before an appearance on the team's weekly offseason talk show, Astroline. "I think about it every day, multiple times."

Whitley, 21, has moved to Houston full-time from his hometown of San Antonio so he can work out at Dynamic Sports Training this offseason and help make up for lost time. Last year, Whitley was suspended for 50 games for a violation of the Minor League Drug Prevention and Treatment Program, and he later went on the disabled list with a strained right lat and a strained right oblique.

As a result, he threw only 26 1/3 innings at Double-A Corpus Christi last year before going to the AFL and dazzling. He struck out 36 batters in 26 innings, finishing with a 2.42 ERA and a 0.96 WHIP.

"The injuries definitely played a huge part in what my main focuses are this offseason," Whitley said.

Staying healthy and reaching the big leagues are his biggest goals for 2019, and Whitley has made some adjustments to his mechanics to help him achieve both of them. That includes working through what he calls a "hip hinge."

"It's mostly to keep my posture straight driving down the mound, and mostly my deceleration pattern," he said. "Starting from the ground up, you kind of want to have those things in check. I slap my back pretty bad when I pitch [on the follow-through], and that's a pretty big mechanical discrepancy. I've been working with a bunch of guys with the Astros to get that in check and hopefully improve the longevity of my career."

Whitley made headlines a month ago when he posted a video on Twitter of him throwing a baseball 110 mph from a short distance and with a running start. The truth? He was using a 3-ounce ball (a standard baseball is 5 ounces) and was trying to fulfill a challenge from Rays prospect Shane Baz, though admittedly knowing he wasn't going to come close to the 117 mph Indians pitcher Trevor Bauer threw a baseball in similar circumstances a year ago.

"It's a good number to hit, but it wasn't anything crazy," he said of the video. "I knew Bauer got up to up like 117. It was the best I've ever done. I was certainly not expecting it to blow up like that."

Whitley will likely open the season in the rotation at Triple-A Round Rock, with a call to Houston to come later in the summer. He's going to be in big league camp for the first time this spring, when he'll get a chance to work with accomplished veterans Justin Verlander and Gerrit Cole . He could be in the rotation with them before too long.

"Hopefully I can stay in a couple of those guys' hip pockets and learn a lot about the game of pitching at the big league level," he said. "Obviously, it's a little bit different of a game than what I've experienced so far. Learn from them, that's pretty much the biggest takeaway I can get from big league camp."