NEW YORK -- Kodai Senga, who has yet to pitch this season for the New York Mets because of a right shoulder capsule strain, will continue working on his mechanics before beginning a rehab assignment.

"With my current mechanics, I didn't think I'd be able to come back at 100 percent," Senga said via an interpreter prior to Monday's series opener against the Philadelphia Phillies. "So taking a little bit of time to look over everything, making sure everything is perfect before I get back into games, is the right move."

Senga said his mechanics didn't feel right during his first live batting practice session April 29. The uncertainty continued after a second batting practice session May 4.

"All my power output was not going toward the catcher," Senga said. "I wasn't able to deliver 100% of it toward the catcher, which is very important. When that is happening, I'm more susceptible to getting hit and also more susceptible to injuries if that continues."

Senga, who signed a five-year deal with the Mets in December 2022 following an 11-year career in his native Japan, and Mets manager Carlos Mendoza acknowledged the differences between how injured players are treated in Japan and the United States.

"In Japan, it's more up to the player -- if the player feels good, they can keep pushing forward," Senga said. "Here the trainers have a very well-structured program."

Mendoza said Senga felt so good after a game of catch Sunday that he subsequently threw 45 pitches off a bullpen mound -- something Senga didn't acknowledge during his meeting with reporters a few minutes earlier, when he said he'd next throw a bullpen on Wednesday.

"It's a unique situation," Mendoza said. "I'm trying to learn the individual myself and trying to get to know him and some of the things that he does and he likes to do."

Senga said he didn't know how many bullpen sessions he would need before he could begin a rehab assignment. The 31-year-old finished second in the National League Rookie of the Year balloting after going 12-7 with a 2.98 ERA and 202 strikeouts last season but reported arm fatigue shortly after reporting to spring training in February.

"At the end of the day, you don't want to put a player at risk, especially if he's not feeling the way he thinks he should be feeling," Mendoza said.