The ulnar collateral ligament (UCL) wasn't torn but had detached from the bone, according to Cardinals general manager John Mozeliak. Harris also had bone spurs removed.
"The ligament itself was not damaged," Mozeliak said Monday at Wrigley Field before the Cardinals-Cubs opened a three-game series. "The integrity of the ligament's fine, but the ligament pulled away from the bone. So, they still [attach] the ligament to the bone the way they normally do, but that's the repair. They just tighten it and secure it, and that's why they predict it's a much less time of recovery."
Harris, who initially broke the news with an Instagram post Monday, was the Cardinals' 13th-round Draft pick in 2008 out of the U.S. Naval Academy. Upon making his Major League debut April 25, 2015, Harris became the first Naval Academy graduate to appear in the Majors since 1921 and just the second ever.
"Great story," Cardinals manager Mike Matheny said. "It's just a setback. You hate to see that happen to any player, especially a player who's had adversity already, not necessarily things on the field, but it's just a tough road. But he's been able to persevere and improve, and hopefully this is still just part of his story of how he's going to have a good career moving forward."
• Mozeliak said backup catcher Brayan Pena, who's on a Minor League rehab assignment for his surgically repaired left knee, is back in St. Louis for two days of therapy before rejoining Double-A Springfield on Thursday. The plan is to make a decision after Pena plays four games with Springfield. The hope is that he's ready to return to the Cardinals at that point.
"When you think back to this offseason when we signed Pena, the whole idea was to create an opportunity to think about how we use [Yadier Molina] and have some more rest baked in," Mozeliak said. "So, my hope is, when Pena's ready, we can exercise it and take advantage of it."
• Randal Grichuk is off to a good start at Triple-A Memphis after being demoted Saturday by the Cardinals. Grichuk went 2-for-8 with a home run and four RBIs in his first two games with the Redbirds, similar to the way Kolten Wong handled a demotion earlier this season. Wong's performance in Memphis earned him a quick trip back to St. Louis, which is what the Cardinals are hoping Grichuk will do.
"Apparently, we send guys down [and] they hit homers," Matheny said. "Kolten did the same, exact thing, just jumped in and got to work and started competing. We're hearing positive things about [Grichuk's] attitude and kind of how he's handled this. That's always a good start. Now, just go and get into a good consistent spot, where he can come back and help us."