DUNEDIN, Fla. -- Aaron Sanchez has the kind of stuff it takes to be one of the best pitchers in baseball. His stuff has also gone missing for long stretches during each of the past two seasons. For these and other reasons, Sanchez is the Blue Jays' Great Unknown for 2019.

Most pitchers would love to have Sanchez's talent: mid-90s velocity with devastating sink which keeps the ball on the ground and generates a lot of weak contact. The issue is that a lack of work over the past two years wreaked havoc on his mechanics, and an arm that should be close to a finished product instead remains a work in progress.

The 26-year-old entered Spring Training last month knowing that he had a lot to prove, not only to the outside world, but also to himself. After two seasons of disappointment, there was an obvious need for positivity, and Sanchez finally got it with successive dominating performances.

"I knew the offseason work I put in was going to make sure I was ready," said Sanchez, who has allowed just three earned runs in 17 2/3 innings this spring. "I wasn't coming into camp hoping, wishing, praying. I knew I was coming in ready to go.

"I'll always be confident when I'm healthy. When I'm not healthy, it's a different story. But good 2019 Spring Training, for sure, especially after all that's gone on the last few years. I'm very pleased."

Sanchez was limited to 36 innings in 2017 because of blister issues, which ultimately resulted in surgery. The following year, he tossed just 105 innings because of an accident that saw his right index finger get stuck in a piece of luggage, which led to another surgical procedure.

The health issues not only kept Sanchez off the mound for long periods of time, but they also impacted his effectiveness whenever he was capable of taking the ball. The blister affected his ability to throw his curveball, and the lack of repetition messed with his mechanics. Suddenly, that delivery wasn't as repeatable as it used to be.

Sanchez averaged career highs in walks each of the past two years with five per nine innings. He also experienced a slight drop in velocity, which was tied to the issues in his delivery. A lot of those problems seem to have been worked out this spring, as Sanchez has been able to locate his fastball. The results have been almost perfect.

"He's looked great to me, and that made me really happy," Blue Jays manager Charlie Montoyo said of Sanchez, who is expected to open the year as Toronto's No. 3 starter. "He’s very important to us, and if he keeps pitching the way he’s pitching, he’s back to normal and that’s good for the Blue Jays."

The version of Sanchez the Blue Jays want to see is the guy who went 15-2 with an American League best 3.00 ERA in 2016. That was supposed to be the start of something great, not the end. It was Sanchez's first full season in the rotation and the final year an "innings limit" was ever supposed to be mentioned alongside his name.

The development then stalled, but with two years of control remaining, the Blue Jays have time to let Sanchez reestablish his value. Whether it's as a trade chip in July, or as part of a surprise success story, Toronto just wants Sanchez to finally be at his best again.

"Going with [Marcus] Stroman and Sanchez into Boston or into Yankee Stadium, you feel good about it, and the whole team feels good about it," Montoyo said. "We have a chance to win. That's all you can ask. He's that guy."