A timeline for his rehabilitation wasn’t given for obvious reasons. The Nationals understandably are reluctant to divulge those details, wary of creating expectations that may not be met. The statement said only that “Murphy’s rehab will begin immediately and will progress throughout the offseason.”

First, a quick, layman’s explainer. Articular cartilage is the tissue at the end of bones that serves as the cushion in joints. A debridement removes pieces of cartilage that aren’t working correctly. Microfracture surgery is done if the defect is considered severe enough. In that procedure, the surgeon pokes little holes into the bone to stimulate bleeding and the blood supplies cells to form a clot that forms new cartilage to fill in tears and holes. The new cartilage isn’t as strong as the articular cartilage so it’s likelier to eventually wear down, but it provides cushioning for some time.

AD

AD

Two orthopedic specialists who haven’t seen the extent of damage in Murphy’s knee but have extensive experience with this injury in athletes said Murphy will likely need at least six months for a full recovery. The Nationals’ season begins on March 29, a little more than five months after Murphy’s procedure, and some sort of rehab games would be likely before Murphy jumps into big-league action.

Dr. Bert Mandelbaum, a co-chair of the Kerlan-Jobe Institute in Los Angeles, and Dr. Luga Podesta, who served as the team physician for the Los Angeles Dodgers and Los Angeles Angels for a combined 19 seasons, said Murphy could need up to 12 months depending on some variables, including the size and location of the defect in the cartilage. They both said it’s usually somewhere in the middle.

“There’s a range. We don’t know this case,” Dr. Mandelbaum said. “The range could be six to 12 months, depending on the size and depth of the lesion. If it’s a relatively small one, it could be on the six-month side. If it’s a big one, it could be closer to the 12-month side. So I hate to put a number on this situation. I’d want to put a range depending on, for example, if it’s a five-millimeter hole, it’s one thing. If it’s a 20-millimeter hole, it’s a different thing. The devil’s in the details and it’s very scalable.”

AD

AD

There are exceptions to the range. Los Angeles Dodgers third baseman Justin Turner, for example, underwent microfracture surgery on his left knee on Oct. 21, 2015 and was on the Dodgers’ 2016 Opening Day roster, though he didn’t start until the team’s fifth game of the season on April 11.

Mandelbaum said people usually are on crutches and use a motion machine to stimulate healing for about six weeks after microfracture surgery. They could begin swimming and biking exercises after about three weeks. A gradual progression is then made over the next three to nine months.

The 32-year-old Murphy finished the 2017 season with the gaudy numbers the baseball world has come to expect from him — a .322 batting average with 23 home runs, 43 doubles, and a .928 on-base-plus-slugging percentage. It was a slight dropoff from his 2016 MVP runner-up campaign, when he finished second in baseball in hitting in his first year with Washington. But it still was an elite offensive season.

Further, he played in 144 games without a trip to the disabled list. But Murphy occasionally missed games with leg soreness, though he usually did not want to talk about it, and went through stretches in which he didn’t look like himself. A step slow. A bit off at the plate. Clunkier. As Baker would often say, Murphy had spoiled everyone with his recent career renaissance so his struggles were magnified. But Murphy seemed off. A significant knee injury makes sense in retrospect.

AD

AD

“The problem with the knee, especially with a baseball player, it affects how they throw and affects the way they hit,” Dr. Podesta said. “So if they can’t pivot on that knee or twist, that could be significant enough to change his throwing mechanics or his swing mechanics. And then he can’t get out of the box to run.”

The Nationals could turn to Wilmer Difo to start at second base if Murphy misses time. Or Murphy’s surgery could impel them to acquire a starting-caliber second baseman as insurance. One potential option is re-signing Howie Kendrick, who batted .293 with an .837 OPS in 52 games after the Nationals traded for him in July.

Regardless, Murphy’s decision to undergo surgery so quickly after the Nationals’ playoff exit was the best possible time for both player and club. It maximizes the offseason recovery time as he enters the final year of his three-year, $37.5 million deal. The Nationals should have Murphy for most of next season and he should have enough time to solidify his value before free agency. The question is exactly how much time. There’s a chance it won’t be the entire 2018 campaign.

AD

AD