“What happens when you have a few on one particular team is that it highlights it,” Hecht said.

Walker’s injury was the simplest. He first felt discomfort in his lower back and tingling in his leg late during the 2012 season, which he thought was caused by the sport’s day-to-day rigors. Some back pain recurred in the years that followed, but never to the degree that it did last season, when he said he also experienced numbness in his leg and foot.

Hecht, who is not involved in the treatment of these Mets players, said lumbar disk herniation like Walker’s is “as common as common can be.” Surgery to repair the injury involves removing only the part of the herniated disk that is pinching the nerve and causing the pain, Hecht said.

Walker, 31, said he completed his physical therapy in less than three months and went through normal off-season workouts. Although he is healthy now, Walker said that he has a regimen of daily exercises and stretches to keep his back in good shape.

Despite the back ailment last season, Walker still hit .282, with 23 home runs and a career-high .823 on-base-plus-slugging percentage. The Mets felt confident enough in his recovery that they gave him a one-year, $17.2 million qualifying offer. Walker accepted, and the sides have talked about a contract extension.

Duda’s injury, a vertebral crack, is another common back ailment in athletes, Hecht said. The usual treatment is rest and rehabilitation.

Before his recent flare-up of back spasms, Duda, 31, said he, too, was regularly doing exercises to support his back. Until last week, there was reason to be optimistic about Duda’s outlook because, after missing 107 games last season, he returned in September to play eight games.

Still, as a precaution, right fielder Jay Bruce took ground balls at first base during workouts on Sunday. Jose Reyes and Wilmer Flores are options to back up Walker; Cabrera, the infielder with the balky knee last season; and Wright.