FORT MYERS, Fla. -- For Lucas Giolito, his Grapefruit League debut in a Red Sox uniform was a chance to gauge the status of his top project this spring: a new-and-improved slider.

Veterans like Giolito don’t take much from linescores in Spring Training, even though the righty had a pretty good one (two scoreless and hitless innings, one walk, one strikeout, 27 pitches, 16 strikes) in the Red Sox’s 8-6 split-squad victory over the Twins on Sunday afternoon.

Instead, it is about identifying key modifications. As far as the slider goes, Giolito feels like he has a better grip on it literally and figuratively.

The modification also shows promise for Boston’s rebuilt pitching department, which has a heavier focus on analytics.

“Little adjustment with the slider,” Giolito said. “Coming into camp, the whole pitching team, they were showing me some data about it, how it was getting a little bit too slow, a little bit too curveball-ish, so we switched up the grip. About a week ago, I started working on that, and I was pleased with how it was coming out. Still continuing to hone that in, but throwing the slider in like the mid-to-high 80s I think is a better move for me.”

Giolito also threw a nasty changeup for a punchout of Emmanuel Rodriguez.

“The changeup is definitely the pitch I go to the most when it comes to offspeed,” said Giolito. “Like on my strikeout on the high one, which I don't do on purpose, but it can be effective. Sometimes it plays off the fastball.”

Giolito’s success in 2024 should have a big impact on whether the Red Sox can be a surprise contender this season.

For a three-year window (2019-21), the right-hander was one of the emerging pitchers in the American League. But in a difficult ‘23 season, he hit bottom, playing for three different teams and giving up 41 homers (the second-most in the Majors).

The Red Sox showed confidence in Giolito’s ability to rebound by signing him to a contract that will pay him $18 million in 2024 and an aggregate $38.5 million over the next two seasons if he exercises his player option for ‘25.

“[Velocity] is up, particularly for [this point in Spring Training],” said Red Sox manager Alex Cora. “He feels the fastball ... velo and quality is improving, which is very important. We faced him a few times [in the past], and the feedback is that when he has his fastball going, he is really good.”

What does a rejuvenated heater tell Giolito about where he’s at?

“It's showing me that my body is working well down the mound for sure,” Giolito said. “I'm not out there trying to throw really hard, but it's coming out pretty good. So just continue on that track. Continue to trust the work that we put in each day to prepare, and hopefully, we continue to maintain that.”

While Sunday was very much a work day for Giolito, he took time to soak in his new environment.

“It felt amazing,” Giolito said. “Sitting in the dugout, the crowd was awesome. I'm not used to Spring Training crowds like that. So I definitely had a little bit of jitters getting back in game action, but I felt good overall. Threw a good amount of strikes. Fell behind a couple guys, but we were able to have a solid outing to start it off.”

The Red Sox hope that Sunday was the first of many incremental steps Giolito will take towards getting back to who he once was every fifth day.

“He was good,” said Cora. “Fastball was good. Changeup was good. Obviously, the walk, he doesn’t want it, but he felt good before the game. I do believe where he’s at right now physically, probably three innings he could have done, but obviously we’re going to stick to the program. But it was a good first outing.”

On a team that has some question marks in the rotation, Giolito has a chance to stand out.

“He’s shown that he’s a great pitcher throughout his career,” said Red Sox third baseman Rafael Devers, who supported his new teammate with a mammoth three-run homer to the opposite field. “He’s somebody that I know can help us. He has great pitches -- we’ve faced him in the past. Yeah, he’s somebody that has been in the big leagues for a while for a reason.”