Aaron Barrett underwent successful Tommy John surgery on his right elbow Thursday, Nationals Manager Matt Williams said. The procedure ended a months-long saga of elbow trouble and frustration, and started a new one — duration to be determined — of work toward returning.

Tommy John surgery typically takes between 12 and 18 months of recovery time. Williams said it’s too soon to tell where Barrett will fall in that spectrum, Pushing to return in a year may not make sense given he would be returning with a month left in the 2016 season.

“Everything was successful,” Williams said. “He’s on the road to recovery now. It’s disappointing for him certainly, but he’s a warrior and he’ll work hard to be back.”

Williams said the rehab is extensive, and that “each guy is different.” In other words, it’s too soon to tell.

“You don’t know. At this point, you just don’t know,” Williams said. “What we can do is make sure he gets the proper rehab, which he will get, and make sure he gets the proper rehab, which he will get, and get strong again. Go through that throwing program he must go through, then make a determination. At this point, there’s no thought on where or when or how.”

Barrett had trouble with his elbow in June, when what was officially described as a right biceps sprain landed him on the disabled list. He returned a month later, only to end up back there within a month with a right elbow sprain. Barrett battled discomfort in the meantime. The Nationals moved him to the 60-day disabled list as he decided to undergo surgery. Barrett appeared in 40 games this season and pitched to a 4.60 ERA with a 1.19 WHIP.

Meanwhile, Michael A. Taylor is not in the Nationals lineup Friday night, though he feels like he could be. Taylor has not played since Tuesday, when he banged his already bruised right knee on the ground in St. Louis. He initially injured that knee last Thursday when he ran into the center field wall at Nationals Park. Williams said the 24-year-old underwent an MRI on the knee Thursday night, when lingering soreness kept him from the lineup. Results came back “good,” Williams said.

“I’m ready,” Taylor said. “I’m not playing today. I’m available off the bench. I think it’s the same thing as before. The swelling came back a little bit, little bit of stiffness.”

Taylor said he thinks the knee is healing, and that barring any setbacks, he should be fully healthy soon. Williams said keeping the rookie out of the lineup — which moves Bryce Harper from right field to center field — is a move made out of caution.

“We’ve gotta make sure we side on the cautious side on that one,” Williams said. “Having that injury, being able to play, and having it flare up again is a concern. He’s fine, but just another day to make sure.”