Columbus Crew SC is in the process of rebuilding a defense that gave up the second-most goals in MLS last season, and now they’ll be doing it without one of their biggest investments.

Head coach and sporting director Gregg Berhalter confirmed that center back Gaston Sauro – who has only played 17 games for Columbus since his acquisition in August of 2015 – will be out for the entire 2017 season, requiring multiple surgeries to repair a persistent knee injury.

Berhalter declined to go into further detail, saying he didn’t “think it’s appropriate to talk about specifics.” But he did say the injury was to the same knee in which Sauro tore a posterior cruciate ligament in May.

“Anytime you’re talking about a guy being out a year, it’s a serious thing; this is no different,” Berhalter told MLSsoccer.com. “It’s going to need a series of operations. We’re comfortable with the doctors that are doing it, we’re comfortable with the diagnosis, and we’re confident that he’s going to make a full recovery.”

But Berhalter admitted that concerns persist about Sauro’s long-term ability to recover from the injury.

“From a player standpoint, there’s always concern when you’re facing an extended period out, so of course we’re concerned,” he said. “But we’re supporting him 100 percent.”

In response to Sauro’s absence, Berhalter said he would “absolutely” be bringing in a starting-caliber center back before next season. But Columbus has also made a center back acquisition for their future who may help sooner than later.

The club announced the signing of homegrown center back Alex Crognale this week, adding one of college soccer’s more decorated products. At Maryland, Crognale was an All-American, Big Ten Defensive Player of the Year, First Team All-Big Ten selection and MAC Hermann Trophy semifinalist, and Berhalter sees big things.

“I think he has a lot of potential, and that’s what’s important to me,” Berhalter said. “We’ve seen him progress every year that he’s been in college, physically, tactically and from his mentality standpoint. He’s developed into a leader, he’s become more dominant on set pieces and overall he’s done a great job of improving.”

Berhalter thinks Crognale can contribute, but doesn’t want to put unnecessary pressure on him. So while he may be capable of starting, Berhalter isn’t assuming anything.

“I think we’re getting ahead of ourselves,” he said. “[Crognale] is a good player and we want to see him develop and want to see him on the field, but I don’t think it’s appropriate to put those expectations on him right now.”

In the meantime, Berhalter and Crew SC will need to figure out how to move on without Sauro, but with his Targeted Allocation Money-level salary. Berhalter said Sauro is over the threshold of salary for cap assistance with a season-ending injury designation, so the club will need to be creative.

“We’d have to restructure his contract, and that’s something we’re working through now,” Berhalter said. “It would have to be a season-ending injury; we’d have to do that for him and then try to get some cap relief.”