CLEARWATER, Fla. -- Jake Thompson pitched the eighth inning in a Grapefruit League game late last month against the Blue Jays.

It seemed unusual, considering Thompson had spent his entire career as a starter. Phillies manager Gabe Kapler said at the time that nobody should read into it, but with Opening Day a little more than a week away, it appears Thompson's future very well might be in the bullpen. Kapler acknowledged as much Monday. It is Thompson's understanding, too.

"They haven't really outright told me, but I think everybody knows," Thompson said a day before he allowed two unearned runs in two-thirds of an inning Wednesday in a 7-7 tie with the Blue Jays at Dunedin Stadium. "They think the slider and split can work in short periods, miss bats and get ground balls. They've built up my pitch count a little bit, so if something happens I can still do both. I'm fine with it. Anything that can get me in the big leagues and stay I'd be willing to do."

Thompson, who has a 1.64 ERA in 11 innings this spring, joined the Phillies as one of the top starting pitching prospects in baseball following the Cole Hamels trade with Texas in July 2015. Scouts rated his slider as one of the nastiest in the Minor Leagues. His fastball touched 95 mph.

But Thompson (4.64 ERA in 18 career starts) has not stuck as a starter. His fastball averaged 90.9 mph last season. He got only 67 whiffs on 341 swings (19.7 percent), a percentage that ranked 374th out of 448 pitchers with at least 250 swings against them.

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In the meantime, other Phillies starters (Ben Lively, Zach Eflin, Mark Leiter , etc.) have passed Thompson on the depth chart.

"I may take off as a reliever," Thompson said. "I've never done it, so I can't say I will or I won't. We'll find out."

Thompson only needs to look at teammate Adam Morgan as an example for why this might be a good move. Morgan resurrected his career after moving to the bullpen. Former closer Ryan Madson came through the Phillies' system as a starter, but he's pitched 12 seasons and made over $30 million as a reliever.

The Phillies believe Thompson's slider and splitter will perform better in the bullpen. Interestingly, a look at the numbers over the past two seasons indicate both pitches' performances have mirrored MLB averages. Thompson's slider had a ground-ball rate of 43.1 percent (MLB average 45.3 percent) the past two seasons, according to Statcast™. His splitter, which has been classified as a changeup, had a ground-ball rate of 45.9 percent (MLB average 49.4 percent).

His slider's whiff-per-swing rate was 34.3 percent (MLB average 35 percent), while his splitter's whiff-per-swing rate was 29 percent (MLB average 31.3 percent).

"He's thrown a lot of sliders in the zone," Kapler said. "So I think we'll see some more chase and some more swing-and-miss when he throws it out of the zone a little bit more. But again, it's a work in progress and there's a lot more homework to be done in that regard."

Thompson said his slider has been inconsistent for the past couple seasons as he focused on establishing his sinker and trying to set up hitters as a starter. Now, he said, he has spent the spring fine-tuning the pitch, knowing he can just step on the mound and throw his two best pitches.

"It's just kind of flipping my mentality a little bit," he said. "It's trying to get swings and misses immediately."

If it becomes the pitch that scouts drooled over just a few years ago, Thompson could become an effective weapon in the Phillies' bullpen. He seems eager to give it a shot.

"I'm usually the first cut in camp," he joked. "It's a lot more comforting here than hanging out in Minor League camp."