Left-hander A.J. Puk's injury-plagued season will come to an official end next Wednesday, when he undergoes surgery to repair his left shoulder. The procedure will be performed by Dr. Neal ElAttrache.

As recently as last week, Puk was showing progress at the A’s alternate training site in San Jose, in an effort to return from a strain in his pitching shoulder. But he suffered a setback on Sunday, when lingering issues reappeared, and he was shut down before throwing to hitters. The A’s had hoped that would have been his final tuneup before returning to the Majors.

A's manager Bob Melvin did not offer specific details about what the surgery will entail.

“For A.J., obviously, it’s been a tough road for him,” Melvin said before the A’s four-game series opener in Arlington on Friday. “Back and forth, ramping up, having to shut down. Obviously, there’s something going on there that needs taking care of.”

Puk, the A’s No. 1 prospect, was expected to be a valuable bullpen piece down the stretch and into the postseason. But he was placed on the 10-day injured list on July 22 and was unable to get healthy enough to work his way back.

Puk appeared in 10 games in 2019 -- all in relief -- posting a 3.18 ERA and 1.32 WHIP with 13 strikeouts across 11 1/3 innings.

Chapman gets second opinion
Melvin said All-Star third baseman Matt Chapman is in Vail, Colo., getting another look at the right hip ailment that has sidelined him since Sunday. He was scheduled to meet with Dr. Marc Philippon, an orthopedic surgeon who specializes in hip disorders.

Chapman was pulled from Sunday's game against the Padres in the fifth inning, and while he has not been placed on the IL, the A’s will likely be able to make an informed decision about Chapman’s immediate future after they hear the results from the latest doctor’s visit.

“It's not unusual to get a second opinion,” Melvin said. “So the fact that he's still on our roster right now ... we should have news on something going on with him, whether he's back soon and playing or not.”

Melvin also said outfielder Stephen Piscotty will likely be back in the lineup Saturday. Piscotty received a cortisone shot in his left wrist Tuesday to alleviate soreness and has been out of the lineup the past two days, though he did pinch-run on Wednesday.

Jefferies to debut
Right-hander Daulton Jefferies will make his Major League debut when he starts the first game of the A’s doubleheader with the Rangers on Saturday.

Jefferies, the A’s No. 7 prospect and the No. 2 pitching prospect behind Puk, split the 2019 season between Class A Advanced Stockton and Double-A Midland, compiling a 2-2 record and a 3.42 ERA over 26 games, including 15 starts.

His strikeout-to-walk ratio is what stands out -- he fanned 93 batters, with only nine walks.

“He's been able to do that right away,” Melvin said. “It's something that's kind of always been there for him. That’s something a lot of pitchers have to work into -- knowing where the baseball is going on a consistent basis. That's never been an issue for him. So as far as that goes, he's ahead of the game.”

Jefferies, who was drafted with the No. 37 overall pick in 2016, had Tommy John surgery that kept him off the mound for two years. His performance in '19 was strong enough to earn him a spot on the 40-man roster.

“He seems to be a real composed kid. He does a lot of the intrinsic things well,” Melvin said. “He's quick to the plate. He's got great command, obviously. He had to go through a couple of issues with some injuries, but he’s finally back to the point where he gets to make his Major League debut. He was pretty excited about that when I told him today.”