CLEVELAND -- Entering his third season in professional baseball, Indians pitching prospect Brady Aiken is about to begin what could be the most important campaign of his young career. The lefty is wrapping up his first completely healthy offseason, and 2018 could serve as a turning point.

The Indians grabbed Aiken with the 17th overall pick in the first round of the 2015 MLB Draft -- a year after he went first overall, but did not sign with the Astros. The left-hander has as good of a pedigree as any pitching prospect, but his path to stardom was put in jeopardy when he underwent Tommy John surgery prior to being selected by Cleveland.

Aiken showed his promise in spurts in 2017, but it was a trying season, as can often be the case for a pitcher working through his first full tour after elbow surgery. He did not feature the 97-mph fastball that he did as a top prospect out of high school -- he now sits in the 87-91 mph range -- but the left-hander has high expectations for himself in '18.

"It's definitely tough just because you know it's in there, the success," Aiken said during the Indians' fall development program in September. "That's not the pitcher I am. It's tough. It's frustrating. This year was frustrating. But at the same time, I learned a lot from the team side, learning about different things that I need to do to get my body in the right state of mind and go out there and compete on every fifth day."

The first two Minor League seasons were not easy for Aiken. Between Rookie ball, Class A Short-Season Mahoning Valley and Class A Lake County, Aiken has registered a 5.05 ERA with 122 walks and 146 strikeouts in 178 1/3 innings.

Aiken has been ranked as high as the No. 64 prospect in baseball before the 2016 season by MLB Pipeline, but the elbow troubles and inconsistency on the mound has caused his stock to slip. The left-hander now ranks as the Indians' No. 24 prospect and did not make the cut for the latest Top 100 prospects list.

But, as frustrating as last season was in terms of numbers, Aiken did achieve his top goal: staying healthy. Aiken led the Midwest League with 27 starts and didn't miss a turn, proving to himself that he isn't fragile.

Without any health complications in 2017, Aiken can finally complete his offseason program at full strength. No need to hold back in throwing drills. No more babying his arm. That should allow Aiken to take a big step forward this year.

"Obviously we want that workload again, but we can focus on pushing him a little bit more when it comes to getting him bigger and stronger and athletic," said Ruben Niebla, the Indians' Minor League pitching coordinator. "This will be his first offseason where he should 100 percent feel like he's healthy, and he's going to be able to go through another full season without any issues and push himself more."

As Aiken grows more agile and athletic, it should become easier for him to repeat his delivery and straighten out his mechanics, which in turn should improve his control. That pinpoint command in the strike zone is usually one of the last things to come back to pitchers as they recover from Tommy John surgery.

That lack of control was particularly frustrating for Aiken, who issued at least three walks in 23 of his 27 starts last season, leading to an oversized 6.88 walks per nine innings. He was throwing quality stuff, but it was not in the strike zone often enough.

Aiken was comforted by the fact that he was eliciting weak contact when opponents were able to put their bats on the ball last season. As an indicator, only 28.4 percent of batted balls against him went for extra bases compared to a 31.7 league average.

Now it comes down to how he can translate those improvements into results on the field. He showed flashes of his potential when he gave up two runs or fewer in four of his last five starts of 2017, and he carries that confidence into the next season.

"It is really, really impressive to see a 20-year-old man -- kid, really -- be able to handle all of the things thrown at him," Carter Hawkins, the Indians' assistant general manager, said. "The fact that he is as resilient as he is is certainly helping a lot of that process, so now it's turning that resiliency, that consistency, into some actual tangible product that hopefully gives him progress over the course of this offseason and really bumps him up to have a really awesome '18 for himself."

Ben Weinrib is a reporter for MLB.com based in Cleveland. Follow him on Twitter at @benweinrib.