BOSTON — Ryan Watson’s push to make the Red Sox’ Opening Day roster will be an interesting storyline throughout spring training.

Boston acquired the 28-year-old righty soon after the Athletics selected him in December’s Rule 5 Draft. He’s subject to the same Rule 5 Draft guidelines, meaning he must remain on the 26-man roster for the entire 2026 season (barring an IL stint) or be placed on waivers.

Chief baseball officer Craig Breslow said last month that the Red Sox have liked Watson for a long time and tried to acquire him a couple times last season.

“We believe a deep mix, a big guy with good extension and good strike-throwing ability that should translate to success in the big leagues,” Breslow said.

So what does his deep mix include?

The 6-foot-5, 225-pounder throws a four-seam fastball, sinker, split-finger fastball, slider and curveball.

The splitter provides another fastball variation that he can throw consistently for strikes and it keeps hitters off his four-seamer, which plays well up in the zone.

“I feel like last year I got into some trouble if I was behind in the count getting too predictable with four-seam usage, especially to the lefties,” Watson said at Boston’s Rookie Development Camp on Tuesday at Fenway Park. “So it’s just another pitch to get them off the fastball and to be able to throw it for strikes, throw it hard.”

His slider — which also has been identified as a sweeper — is his best secondary pitch.

“It’s more horizontal than depth,” Watson said. “A lot of right to left horizontal movement.”

His curveball has much more depth to it.

“Last year I started throwing it a little more than I have in years past to both sides of the plate, righties and lefties,” he said. “So just try to throw it aggressive and let it bite.”

Why did he begin throwing it more often?

“I fell into some predictability, situations where I started getting a little predictable,” he added. “So being less predictable and really just using it as a weapon. It’s a good pitch. And it’s not just good to one side of the plate. I can throw it to both. So really just kind of running with that. Just giving something other than the slider sometimes helped a lot.”

Watson posted a 4.26 ERA in 46 outings (50 ⅔ innings) at Triple-A Sacramento last year. He averaged 11.4 strikeouts and 2.8 walks per nine innings.

The Sox added a couple of pitchers with above-average extension this offseason. Both Watson and 26-year-old Tyler Samaniego extend far down the mound, leading to hitters having less time to react and their fastballs looking even harder.

“I play the extension and the release-angle game,” Watson said. “So it (the four-seam fastball) plays with the angles and stuff. But the sinker is a pitch I think we’re really trying to throw more of. It’s a good pitch and I just feel like it’s going to be a good weapon for me.”

He topped out at 97 mph with his fastball last year.

“Really sat in that 94 to 96 range,” he said. “I’d like to be 95-plus with the fastball.”