DUNEDIN, Fla. -- Shun Yamaguchi's Grapefruit League debut Monday highlighted some of the challenges for a pitcher transitioning from Japan to the Major Leagues, which start with the ball itself.

Yamaguchi recorded just two outs on 29 pitches in the Blue Jays’ 4-3 win over the Braves, allowing three runs on three hits, a walk and a hit batter. The right-hander certainly wasn’t missing by much, but those critical inches on either side of the plate could take some time for him to hone in on.

“The ball itself is slightly bigger,” Yamaguchi said following his start. “The seam, it’s a little lower than the ones in Japan, so I’m trying to make adjustments there.”

This isn’t all bad for Yamaguchi, though, who felt that the different ball helped him create more movement on some of his pitches. He made a point, several times, of saying that this is something he’ll simply have to adjust to. When he does, those edges will be easier to find.

Monday wasn’t the first step that Yamaguchi was looking for, especially after Trent Thornton looked sharp in his Saturday debut. With Ryan Borucki ruled out of the competition for the No. 5 rotation job after being shut down with left elbow tightness earlier this spring, Yamaguchi and Thornton are going head-to-head for that final spot.

Regardless of role, general manager Ross Atkins is confident that Yamaguchi’s game will transition well to the Majors.

“What he’s done, we believe in,” Atkins said. “We also believe guys that get the amount of strikeouts he did, in a contact-driven game in Japan, is something that will translate well.”

Thornton appears to be the early favorite for the fifth starter’s job, but it needs to be viewed through a wider lens than two pitchers competing for one outcome. Yamaguchi has a history of success as a reliever with Yokohama in the Japan Central League, where he recorded 111 of his 112 career saves from 2009 to 2013, and the Blue Jays believe in him as a reliever, if that’s how this breaks.

In a way, that versatility could work against Yamaguchi’s candidacy for the rotation. Thornton is a starter and a starter only, but Yamaguchi’s bullpen potential -- in which he could pitch single innings or stretch into a valuable multi-inning role -- could allow the Blue Jays to have the best of both worlds and keep both pitchers on the roster.

It will also be important to monitor how comfortable Yamaguchi looks as he ramps up in a Major League Spring Training for the first time. The Blue Jays work to adapt their programs to incoming players, especially those who are veterans with their own, established routines, but Yamaguchi is used to a heavier workload in Japan, where pitchers typically throw a higher number of pitches.

Bullpen alternatives will be a factor here and, of course, this conversation is one injury away from both pitchers landing comfortably in the rotation together. Until then, the Blue Jays will continue to evaluate this from every angle.

“The combination of alternatives and effectiveness,” Atkins said. “His effectiveness as a starter, which will probably be largely based on fastball command, and then what our alternatives are and what it is weighing against.”