MESA, Ariz. — The talk of the first day of full-squad workouts for the Cubs surrounded their presumptive, Opening Day third baseman Matt Shaw.

But it wasn’t for the right reasons, as manager Craig Counsell announced he was dealing with oblique soreness.

Saturday morning, the Cubs’ 2023 1st-round pick was one of the first players out onto the field, taking ground balls at the hot corner.

“He’s not [a] full participant, but he’s kind of gradually increasing activity,” Counsell said Saturday afternoon. “So, yeah, feeling good, but going slow with the gradual increase in activity.”

After the team missed out on free agent Alex Bregman earlier in the week, the attention shifted quickly to Shaw, who Cubs president of baseball operations Jed Hoyer had earmarked as being in contention for the role in December.

But the injury slowed things — but it doesn’t mean the Cubs are going to rush him, either.

“I think we’re gonna be cautious,” Counsell said. “We’re getting a number of good days back-to-back right now. [If] every day is a good day, the next day we’ll increase activity a little bit.”

Assad’s mysterious injury

Javier Assad still isn’t sure how he suffered a mild strain in his left oblique.

He arrived home last week after a bullpen session and at some point later that night, he was in pain.

“I threw a bullpen that day, I felt good, and I went home and then — I don’t know when exactly — I felt it,” Assad told Marquee Sports Network in Spanish.

[MORE: As Cubs camp heats up, Nico Hoerner’s recovery timeline remains murky]

Assad is totally shut down from throwing right now. He received an MRI earlier in the week that produced the diagnosis, and his recovery process currently is strengthening the area.

It’s still too early in the process for Assad to know whether he’ll be ready for the season opener in Japan in a little over a month, but he wants to be healthy and return to pick up where he left off last season. Last season, Assad had a 3.73 ERA in 29 starts (147 innings) and was a key figure in the Cubs rotation.

“There’s nothing to do now, it happened and I’m just working on trying to get healthy quickly and come back and — God willing — help the team,” Assad added. “We’re going day by day in how I feel and depends how I feel each day and we’ll see what happens. The first thing and most important thing is to be healthy.”

Setback for pitching prospect

Prospect Brandon Birdsell was the other pitcher who started camp slow after dealing with a lat issue.

Saturday, Counsell said that the Cubs’ 2024 minor league pitcher of the year had an MRI and was diagnosed with a grade 1 lat strain.

“So, it was three to four weeks no throwing and then we’ll progress,” Counsell said. “So, overall, good news. It’s a little more significant than some of the other guys, but you could absolutely see him pitching in April again.”

Air Shota

Before morning stretch, Shota Imanaga grabbed a basketball and showed off some of his skills on a net next to the agility field at Sloan Park: