When assembling a roster, Derek Falvey said Thursday, catching falls into the same category as pitching.

“You never feel like you have enough,” the Twins’ chief baseball officer said. “And it’s difficult to get good catching.”

That instinct became gospel this week, when the Twins learned Jason Castro, who had started 124 of the Twins’ 202 games since his arrival in Minneapolis last year, would not play again this season after undergoing knee surgery.

Castro had not produced much at the plate this season — only nine hits, including one home run, in 63 at-bats (.143), a falloff presumably related to his nagging knee pain — but there was no doubt he was trusted by the pitching staff and valued by his manager.

Now the Twins face 4½ months of filling that vacancy, with no clear solution. Rookie Mitch Garver figures to be given the opportunity to make himself as valuable as Castro, and to fulfill the faith Falvey and General Manager Thad Levine showed in him last December by declining to bring back Chris Gimenez. Bobby Wilson, a 35-year-old career backup who has played for six different major league teams, was signed in November to provide leadership and defense should a situation like this arise.

Falvey and Twins manager Paul Molitor both expressed confidence in that duo Wednesday. Garver, after all, was the Twins’ minor league player of the year in 2017 and excelled, particularly as a hitter, at every level during his minor league career. Wilson has 16 seasons of pro experience to draw upon, and has the endorsement of Twins All-Star righthander Ervin Santana.

“He’s very smart. One of the best, smartest catchers I’ve ever worked with,” Santana said during spring training.

He pitched to Wilson 35 times, including his 2011 no-hitter against the Indians, while they were teammates in Anaheim.

“He just put the signal down, and I threw it,” Santana said of his no-hitter.

Garver sounded confident he is ready for increased playing time.

“It’s going to be a learning experience. But every game is a learning experience,” he said. “Whether it’s pitch-calling or defense or offensively, you just try to pick up something every day and improve.”

But Falvey made it clear, too, that he already has begun the process of acquiring another catcher, whether for the major league team or as minor league depth. It’s a real need, because Wilson’s promotion from Class AAA Rochester leaves the Twins’ system bereft of catchers with major league experience. In fact, they don’t have anyone with even 60 games of Class AAA experience.

“We’re going to pursue potential opportunities to upgrade,” Falvey said. “We have been prepping for [acquiring] depth, and we are now expanding that search, knowing we’re going to have the chance to have somebody impact us for the full season.”

One challenge for Garver, Wilson and any newcomer will be to replace Castro’s ability to turn borderline pitches into called strikes. By most published rankings, Castro is one of the top five pitch-framers in the major leagues. That’s a skill the other Twins catchers have tried to improve upon, with Castro’s help.

“I review the previous game every day. Try to see how I did, how I can get better, and then I work on it in the bullpens,” Garver said. “We’re in the midst of changing some things, especially how we receive low balls, trying to get better at that. It’s something I’ve worked on a lot. I’ve seen glimpses of [progress]. I’ve got a few calls on low pitches, and it really helps out my receiving numbers. There are other times when I go back to old habits, and I’m trying to eliminate those.”

For Wilson, pitch-framing was a midcareer revelation, and he’s now considered above average at it.

“I always thought I caught the ball pretty well, but there are new techniques now. I’ve learned some new wrinkles to help my pitcher get more strikes,” Wilson said. “We pay a lot more attention to it now than I ever did when I came up.”