TORONTO — During the fourth inning of his second start of the 2017 season, Taylor Guerrieri threw a pitch and felt a pull in his right elbow. Not a shooting pain. A grab, a tug. A sensation he unfortunately recognized. As he watched a trainer jog out to the mound, his mind went immediately to one place: Tommy John.

“Oh, yeah — that was my first thought,” he says. “It was scary as hell. I thought I was done.”

He’s had it before — in 2013, when he tore his ulnar collateral ligament and underwent Tommy John surgery to correct it. That kept the then Tampa Bay Rays prospect on the shelf for nearly 12 months. A second surgery could have been the quietus of his career.

But this time, tests revealed Guerrieri had a UCL sprain, not a tear, and that what he needed was rest. He certainly got it, sitting out the remainder of 2017 after pitching only 9.1 early-April innings.

Come winter, he was on waivers. Which is where the Toronto Blue Jays claimed him from the Rays, the only price paid a nominal waiver fee. For a 25-year-old who was once one of the game’s top pitching prospects, it was a wake-up call.

Now, Guerrieri starts over — with a new organization, a live arm he hopes is finally healthy, and another chance to prove he can finally fulfill his potential.

“Safe to say things didn’t go the way I planned over in Tampa,” Guerrieri says. “I just ran into some bad luck and my health wasn’t there for me. But I’m feeling good again. I’m feeling normal. So, I’m looking to build off of where I was when I was healthy. If I can get back there and stay healthy, I’ll be a happy camper.”

Since he was drafted 24th overall in 2011 out of Spring Valley High School in Columbia, S.C., and given a $1.6-million signing bonus to become a professional, Guerrieri’s once promising career has been a tumultuous one.

There was the Tommy John surgery in 2013, shortly after he’d been selected to pitch in the MLB futures game. There was the 50-game suspension served in 2014 after he tested positive for a drug of abuse, which is baseball’s way of describing a recreational drug like cannabis. Then, in 2017, the UCL strain, which wiped out yet another season.

That setback was especially tormenting as the Rays were ready to finally take the reins off their first-round pick. Guerrieri was brought along slowly out of high school, throwing only 119 innings over his first two professional seasons. The Rays were conservative with his workload following surgery as well, deliberately building him up to a career-high 146 innings at double-A in 2016.

Added to the 40-man roster that winter and starting 2017 at triple-A, Guerrieri was finally going to have a chance to pitch without restriction every five days. And if the Rays had an opening in the majors, and Guerrieri was pitching well at the time, he would have been a very strong candidate for his first major-league call-up.

Instead, his 2017 was spent rehabbing, as Guerrieri received rounds of platelet-rich plasma and stem cell injections in his elbow to aid healing. Ultimately, he lost a battle with the calendar, and was unable to return to full speed before the end of the minor-league season.

But he did work his way back to throwing bullpens by fall, and started his normal off-season throwing program on time and without incident in mid-November. Barring the unexpected, he’ll be ready to go for the beginning of Blue Jays spring training next week.

“The whole process was a grind — it wasn’t fun,” he says. “But, towards the end, I started to feel stronger and stronger. And I feel strong now, too. I’ve been throwing every day, throwing as far as I want to. I’m ready to keep going.”

There’s no denying Guerrieri’s stuff, which is why he continues to get opportunities. Blessed with terrific arm speed, he leans on a two-seam fastball with sharp sink that generates plenty of groundballs, and uses a hard curveball as his swing-and-miss out pitch. He mixes in a cutter and change-up as well, pitches the Rays insisted he develop in order to round out his repertoire.

Although he once threw in the high-90s as a high-schooler, Guerrieri’s no longer overpowering. What he does do is fill the zone with strikes, producing elite ground ball rates with some strikeout upside that doesn’t always show up in his numbers because he pitches so often to contact.

That’s why, in 2013, MLB.com considered Guerrieri the No. 44 prospect in the game, while Baseball Prospectus had him at No. 48. Even as recently as 2016, Prospectus ranked him at No. 84, saying “Guerrieri’s stuff may merit a higher place on this list.”

And despite his many hiccups since turning pro six years ago, Guerrieri has been undeniably effective when able to pitch. He boasts a 2.51 ERA over 361.2 career minor-league innings. He’s limited walks (2.1 BB/9), kept the ball on the ground (he has groundball rates of 61 per cent or higher in six of his seven seasons), and suppressed power, allowing only 18 home runs (0.4 HR/9) over his career.

“In high school, I could just blow it right by guys. But in pro ball, I’ve learned to pitch a little bit,” he says. “I’ve learned how to work the corners, learned how to pitch to contact. It’s helped me a lot.”

So, where does he fit in? Well, Guerrieri’s been a starter since he first picked up a baseball, but when he met with the Blue Jays this winter the club asked him how he felt about the bullpen. He’s made only four relief appearances in his career. But after finding himself on waivers this off-season, Guerrieri’s not turning down any opportunities.

“I’m definitely up for the task,” he says. “I’m preparing for a starting job. So, my arm’s going to be in shape for either starting or relieving. But I’m ready for whatever they throw on the plate.”

Now, that doesn’t rule out Guerrieri beginning the season as a starter, especially if Toronto suffers injuries in the major-league or triple-A rotations. But a relief role would help limit stress on Guerrieri’s elbow. And with the Blue Jays having traded right-hander Dominic Leone last month — and a big-league relief corps being the revolving door it is — the bullpen may be Guerrieri’s clearest, and quickest, path to the majors.

In fact, Leone could be a fine template. He, too, was an off-season waiver claim, plucked from the Arizona Diamondbacks in November 2016. He won a job in Toronto’s bullpen during spring training, and ended up logging the second-most relief innings on the team, pitching to a 2.56 ERA in the process.

It’s certainly something to keep an eye on this spring. Either way, Guerrieri’s just happy for a fresh start, and for his health. When he last walked off a mound in April, he thought his career might be over. It’s been a long nine months since.

“Honestly, I watch a lot of video of myself to kind of say, ‘Hey, you still got it, man. It’s still there. Just get back to where you were,’” Guerrieri says. “And I just wake up every day and think positive things. If you come to the park with a negative attitude, I think there’s a better chance of something bad happening.

“Leaving Tampa was definitely bittersweet. But being with Toronto is great. I love being the new guy. I’m just so excited for the opportunity.”