PITTSBURGH -- As Vince Velasquez sat at his locker in the visiting clubhouse of T-Mobile Field on May 28, he expressed optimism that he would pitch again this season. Velasquez had just landed on the injured list after re-aggravating his right elbow in his first start off the injured list -- an injury that had already caused him to miss several weeks -- but the right-hander didn’t believe surgery was the answer.

“I can’t really put a timeline on it, but I could honestly say I’m really optimistic about the fact that I’ll definitely throw again before the end of the year,” Velasquez said then.

Surgery, however, was the answer.

Velasquez underwent season-ending surgery on Wednesday performed by Dr. Neal ElAttrache to address damage to his right ulnar collateral ligament (UCL). Per director of sports medicine Todd Tomczyk, Velasquez should be able to return to throwing in four months with a return to competition in 11-12 months.

“You definitely feel [for him],” said manager Derek Shelton. “Anytime you lose a guy to injury, I think the easiest thing for us all to look at … the baseball player side. When you spend a ton of time with someone, the human being side of it is the side I hope we can make people feel better.”

Velasquez, who had a 3.86 ERA in eight starts this season, is the third starting pitcher on the Pirates’ 40-man roster to undergo season-ending surgery this season. JT Brubaker and Mike Burrows, the Pirates’ No. 8 prospect per MLB Pipeline, both had right-elbow UCL reconstruction surgeries with a projected return to competition in 14-16 months.

Tomczyk emphasized that Velasquez’s surgery was not Tommy John surgery. Rather, it is a hybrid between a reconstruction and a repair, explaining why Velasquez’s timeline differs from that of Brubaker and Burrows. Velasquez previously experienced issues with his right elbow, undergoing Tommy John surgery in 2010 and missing all of the following season.

On May 4, Velasquez exited his start against the Rays after three innings due to right elbow discomfort, then hit the injured list the following day due to right elbow inflammation. On May 20, Velasquez made a rehab start with Triple-A Indianapolis. Following the outing, Velasquez felt he was where he needed to be, both physically and mentally. On May 27, Velasquez departed after two innings due to right elbow discomfort.

“Unfortunately, what we’ve learned throughout the years with players who’ve had UCL reconstructions, sometimes all the clinical exams and the diagnostic studies will be clear. Then, you go through the rehab progression. Then, you get to the point where it’s just not functional. Unfortunately, for Vince, that was the situation,” Tomczyk said. “He didn’t feel any significant pain, got through his rehabs, got through his throwing progression and then when he came to perform at a high level, he had these recurrent symptoms.”

Coming into Spring Training, the Pirates had eight starting pitchers on their 40-man roster who stood to contribute innings: Brubaker, Burrows, Velasquez, Mitch Keller, Roansy Contreras, Rich Hill, Johan Oviedo and Luis L. Ortiz. Now, the Pirates are down to five and will have to figure out who else can provide this season.

Quinn Priester, the Pirates’ No. 4 prospect, could pitch Major League innings at some point this season, but he will likely spend more time in Indianapolis before earning his first callup. In 12 starts there, Priester owns a 4.63 ERA and 3.66 FIP across 56 1/3 innings. Caleb Smith is the only pitcher on the Indians’ roster with significant starting experience -- Smith has a 5.00 ERA across 64 MLB starts -- but the southpaw is currently on the seven-day injured list.

“We’re going to have to have different guys step up, whether it’s guys that are here or guys within the organization. Just like when we’ve lost relievers or position players before, then the next guy’s gotta step up,” Shelton said. “It tests our depth a little bit.”

Velasquez’s surgery affects how the team plans to handle Contreras. Prior to Velasquez’s injury on May 27, the team planned to temporarily move Contreras to the bullpen due to the 23-year-old’s recent struggles (5.64 ERA and 6.69 FIP in four starts in May).

Contreras pitched in relief on May 28, but the Pirates brought him back into the rotation in place of Velasquez. In Contreras’ two starts since rejoining the rotation, the right-hander has allowed 12 earned runs in 4 1/3 innings. On Wednesday, Contreras allowed seven earned runs and recorded one out before his afternoon ended. Shelton said the team has yet to make a decision regarding Contreras’ role.