Will Phillies’ Andrew McCutchen still be elite after return from knee surgery? Even medical experts don’t know for sure.

Andrew McCutchen batted .709 as a high school senior. Of the 1,501 players drafted in 2005, he was taken 11th. He’s a five-time All-Star, a Gold Glove Award winner, and the 2013 National League MVP.

And he did it all after blowing out his right knee at age 16.

Let that serve as context for McCutchen’s response to a Feb. 17 question about feeling nervous that he will make an equally successful recovery from having the torn anterior cruciate ligament in the middle of his left knee reconstructed with a tendon grafted from his quadriceps last June.

“No, [because] there’s no ‘hope’ in my mind. There’s a ‘know,’ ” the Phillies left fielder said. “I know what I can do, I know what I’m going to do, and I know what I am doing. That’s the end of it.”

OK, so McCutchen’s confidence is as strong as ever. Even after the Phillies ruled him out for the original March 26 season-opener in Miami, he vowed to play on March 27, a goal that didn’t even seem overly ambitious once manager Joe Girardi said McCutchen likely would be ready at some point in April.

But while there’s little doubt that McCutchen will return to the field, it’s fair to wonder if he will be able to do so at his previously elite level of performance, according to multiple medical experts.

For one thing, ACL repairs are far less prevalent among professional baseball players than their football, basketball, and soccer counterparts. For another, McCutchen is older than the average athlete who overcomes major knee surgery. And even considering the recent dip from his career peak (.262/.358/.447 from 2016 to 2019 compared with .302/.396/.509 from 2011 to 2015), he’s still 15% more productive than the average major-league player based on adjusted-OPS, a high bar to meet upon his return.

“At 33 years old, he may take a little bit longer and his performance may be a little bit slower to get back to that,” said Stan Conte, formerly the head athletic trainer for the San Francisco Giants and Los Angeles Dodgers. “It doesn’t take a rocket scientist to know younger people heal better than older people.”

In 2014, Conte co-authored a study that attempted to determine if baseball players who had ACL surgery experienced a decline in performance upon returning to play. The results were mixed because, by Conte’s admission, the sample was too small.

Using publicly available information and studying only big-league position players (no pitchers or minor-leaguers), Conte and his colleagues found only 26 players who had ACL surgery over a 13-year period from 1999 to 2012.

Of those, 88% returned to play, albeit in an average of 21.2% fewer games, in the season after surgery. Interestingly, players who injured their rear batting leg saw a 12.3% dip in batting average; those who injured their front knee, as McCutchen did, witnessed a 6.4% uptick.

“At the time it was a decent study,” Conte said by phone. “Nobody had ever looked at ACLs in baseball before. But with small sample sizes you can get fluctuations. I think it was valuable at the time because it helps the next guy write the next study.”

The next guy was Brandon Erickson, an orthopedic surgeon at the Rothman Orthopaedic Institute in New York and one of the Phillies’ assistant team physicians.

Last year, Erickson and six fellow doctors published a more exhaustive study. With access to Major League Baseball’s Health and Injury Tracking System database and incorporating pitchers and minor-leaguers, they found 124 players (but only 21 major-leaguers) who had ACL repairs from 2010 to 2015. Of those, 80% returned to play.

Erickson’s group also tracked the players’ performance before and after surgery and matched it to a control group of comparable, healthy players. The result: 73% of ACL survivors maintained their previous level or saw improvement.

“We look at that study more than we look at my study,” Conte said, “and when you start looking at it, you have a lot of confidence with the Erickson study that a player will come back to their previous level of play.”

But because Erickson’s study was more inclusive and featured predominantly minor-leaguers, it skewed younger (mean age: 23.7). Do the encouraging findings apply to players who are, say, 10 years older and might face a different set of challenges?

“That’s a great question,” said Fotios Tjoumakaris, also an orthopedic surgeon at Rothman Orthopaedic Institute (Erickson recused himself from discussing McCutchen’s case because of his affiliation with the Phillies). “It’s such a good question, in fact, that it kind of means that a study like that needs to get done.”

Here’s the problem: The population of big-leaguers in their 30s who have had ACL surgery is minuscule.

Years ago, Tjoumakaris studied the rate of recovery for ACL patients over age-40 and under age-25 and found “really no differences.” Most of the cases weren't athletes, though, and certainly not elite-level ones.

“Absolutely I think it’s a lot harder with a guy over the age of 30,” said Tjoumakaris, who performs ACL procedures on high school and college athletes and worked previously with Freddie Fu, McCutchen’s surgeon at the University of Pittsburgh Medical Center. “Everything would need to be done for him -- optimizing his nutrition, making sure that his rehab goes completely according to schedule. I do think it’s much harder for him to get back to that level.”

Washington Nationals outfielder Adam Eaton made a successful return from ACL reconstruction. He batted .287 with a .797 OPS over the last two seasons, production that compares favorably with his pre-op .284 average and .774 OPS. But Eaton was 28 when he got injured in 2017.

Among other notable baseball players who came back from ACL procedures, Chicago Cubs outfielder Kyle Schwarber and then-Toronto Blue Jays pitcher Marcus Stroman were in their 20s. Hall of Fame closer Mariano Rivera made it back at age 42.

McCutchen concedes that this recovery wasn’t as easy as when he was in high school. He was still growing then, and his body responded differently to both the trauma of the injury and being pushed during the healing process.

But McCutchen also learned not to take any shortcuts in his rehab and to derive satisfaction from baby steps. It’s probably why he didn’t object to the Phillies’ plan of placing him on the season-opening injured list. McCutchen, who signed a four-year, $50 million contract before last season, had not yet tested his knee in a game situation when spring training was suspended because of the coronavirus pandemic.

Medical experts agree that typical recovery time from ACL surgery is 10 months. But it usually takes an extra month or two before a baseball player can expect to be back to game speed, according to Conte.

Conte applauded the Phillies for taking it slow with McCutchen, although he noted that many teams still wind up giving in to the urge to bring back a player too soon even if it’s unintended. Given the likelihood that opening day won’t occur until at least early June -- 12 months after McCutchen’s surgery -- Conte said that risk is minimized significantly.

"Maybe you start the season June 1, God willing, which really gives him a chance to make sure this is completely healed and his leg is strong enough,” Conte said. “The only negative here -- and I don’t even see it as a negative -- is his age. But we have seen a lot of 33-year-old outfielders have really good years.

"You have to measure him against a person like himself, which is hard because he’s a special guy as far as being a baseball player. You can’t compare a 33-year-old part-time outfielder to McCutchen. He’s not going to degrade as much as the other guy. Let’s just say the [new] cruciate ligament should get him back to where he was. Now he will just be a year older. That’s all.”

Tjoumakaris arrived at a similar conclusion. Although he acknowledged that age is the one variable that is unaccounted for in McCutchen’s case, it isn’t insurmountable.

“Given his style of play, his history in the league, yeah, I think he’s going to make a pretty good recovery,” Tjoumakaris said. “And because baseball’s a naturally low-risk sport for ACL, I think everything’s in his favor to have an optimal outcome.”