TORONTO -- If you're a Blue Jays fan searching for reasons to be excited about the upcoming season, look no further than the return of Aaron Sanchez .

A healthy Sanchez could give the Blue Jays one of the best rotations in all of baseball. Without him, the group as a whole might be average at best. The fact that this could go in such polar-opposite directions is what will make Sanchez's journey through Spring Training so compelling to watch.

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There were lofty expectations for this staff a year ago, but that was before J.A Happ missed six weeks with an elbow issue and Sanchez hit the DL with a blister on his right middle finger. In the end, Sanchez went from someone who was considered a potential American League Cy Young Award candidate to a guy who was limited to 36 innings because of an injury that just wouldn't go away.

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"He's key. When he's not in there, it's a big gaping hole," Blue Jays manager John Gibbons said. "We tried to fill it different ways last year, and it didn't really work. I've talked to him a couple of times, he feels really good, and barring any setbacks, I don't think there will be any issues. We'll see."

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The tricky thing about blisters is that they are so hard to predict. Some pitchers find a solution that works for them and it never becomes a serious problem again. Others have been haunted by the issue throughout their careers and never escape it. In some ways, Sanchez's situation is impossible to predict, but the good news for Toronto is that, as of now, there are no immediate concerns.

Sanchez began throwing without any problems in January and will be a full participant in Spring Training. Toronto also is quick to point out that his season-long issues in 2017 weren't entirely related to his blister. While rehabbing the injury, Sanchez also sustained damage to a ligament in his right middle finger. That problem has been resolved and it's unlikely to surface again.

If Sanchez does find a way to overcome the blister, there's no telling how good he might be this season. In 2016, Sanchez finished 15-2 with an AL-best 3.00 ERA and what's easy to forget is that he did all of that during his first full season as a starter. His overpowering sinker and sweeping curveball became staples, but if he can master the changeup, then he'll become even more dangerous.

Sanchez understandably grew tired of all the questions about blisters during the trying 2017 season, but he hasn't escaped them quite yet. Every pitch he throws this spring will be closely monitored. Every glance at his fingertips will be scrutinized. And every spring start he gets through without any issues will bring the Blue Jays one step closer to their ultimate goal.