FORT MYERS, Fla. -- For weeks, the combatants for the last spot in the rotation seemed clear enough for the Red Sox.

Garrett Whitlock, Tanner Houck and Josh Winckowski were in competition for one spot. With this week’s unwanted curveball -- Lucas Giolito is out indefinitely with right elbow woes -- it seemed that two of those three could crack a rotation that also includes Brayan Bello, Nick Pivetta and Kutter Crawford.

But in recent days, chief baseball officer Craig Breslow and manager Alex Cora have added another name to the mix.

Don’t overlook Cooper Criswell, who has a chance to go from relative anonymity to a spot in the rotation.

At times, Criswell looked ready to play the part on Wednesday at Hammond Stadium, such as when he sent down the first six Twins batters he faced.

But in the third the righty with the three-quarters arm angle got in a jam he couldn’t escape and Edouard Julien belted a three-run homer.

However, an evaluation won’t be made on that one mishap, not as Criswell is in the process of getting stretched out.

“First two innings, I felt great, felt like I was throwing all four pitches where I wanted to, any pitch, any count,” Criswell said. “Obviously third inning, that wasn’t the case. So obviously, I missed some spots there. I wish I could have cleaned that up some for a better third inning. But all in all, I think there's some positives to take away from today and then some things that obviously you can go back and work on and hopefully turn out better for the next outing.”

When the Red Sox signed Criswell to a one-year, $1 million deal on Dec. 12, it hardly made a ripple or a headline.

But Breslow and the men leading the club’s new pitching infrastructure identified someone whose stuff could tick up in their program.

The last few weeks have only solidified that notion.

“It would be unfair to say we overlooked him but we just weren’t as familiar with him given that he wasn’t with us,” said Breslow. “But I think what has been impressive and what we knew we were getting is an elite strike thrower. I think there were some questions as to whether or not we could help boost the stuff. I think in pretty short order, it's ticked up a little bit while maintaining the ability to shape pitches very, very well and pound the strike zone. So I think he's definitely put himself in the conversation.”

Criswell, 27, has made just 12 appearances in his career, 10 of which came last season with the Rays. His career Major League ERA is 5.97. Over 86 Minor League appearances, his ERA is an unspectacular 4.43.

The Red Sox think there is more there.

“Criswell is a guy that even before this happened [with Giolito], we've been talking about him in the rotation. He has a chance,” said Cora. “He’s very, I don’t want to say unique, but his look is different. He has that sinker-slider combination, and the slider is really good. He's gaining confidence, he’s gaining velocity too.”

Wednesday was one of those days Criswell didn’t have his best velo, as he topped out at 89.3 mph. But the grind of Spring Training is one in which velocity often fluctuates.

The important thing is that Criswell feels he is taking to the revamped Boston pitching program.

“For sure, yeah, I feel like the cutter has been the main pitch that we've been focusing on and the shape of it is getting where we want it to be,” Criswell said. “And then after that, trying to tick the velo up here and there as we can.”

There are also the off-field training changes.

“So I started the weighted ball program trying to increase the velo with [pitching coach Andrew Bailey],” Criswell said.

Criswell is never going to be a flamethrower but he thinks he can succeed even in an age where velocity has become king.

“I feel like if you have four pitches that you can throw for a strike at any point in the count, that helps keep the hitter guessing,” Criswell said. “Obviously, some guys value velo more, some guys value strikes more. At the end of the day I feel like it's a good mixture to have a group of guys who can do a little bit of it all.”

As far as Boston’s mix of pitchers goes, it seems increasingly likely that Criswell is going to be part of it.