FORT MYERS, Fla. — Nearly two full weeks into spring training, dozens of accomplished free agents around the major leagues are still unsigned.

There’s a new rule limiting visits to the mound, too, creating at least some early confusion about how to keep track.

So while their collective bargaining agreement runs through four more seasons, players have been expressing more frustration with owners lately than usual during an offseason marked by increased tension between the sides.

“The goal of collective bargaining is not labor peace. It’s a fair and equitable deal. Fifteen months in, we’re seeing things that we’ve never seen before, and that raises concerns,” union leader Tony Clark said. “We’ll have to figure out in the near term and in the longer term how those concerns can be addressed, because invariably if they are affecting the industry adversely, everybody should have that concern.”

Clark began his annual tour of camps on Saturday with Boston. Clark said after the meeting in the Red Sox clubhouse that the union’s special training camp for free agents in Bradenton will stay open indefinitely. About one-third of the 166 players who exercised free agency rights last November have not reached a contract agreement, including stars like starting pitcher Jake Arrieta and third baseman Mike Moustakas.

Signings have begun to pick up over the past week, though. Clark acknowledged not every player will find a team.

“We’d love everybody to be signed,” he said. “But the truth is at the end of every offseason, in every year you go back to as far back as I can recall, there are always guys who are at home at the end of the offseason. The key is going to be at the end of this one, seeing where we are and perhaps if there’s an explanation as to why, and then determine based on that explanation, assuming there is one or there isn’t one, try to appreciate what the next steps might look like.”

Major League Baseball, in a statement earlier this month, attributed the number of unsigned players to a misreading of the marketplace and denied any deliberate attempt at fielding noncompetitive clubs.

“In baseball, it has always been true that clubs go through cyclical, multiyear strategies directed at winning,” the MLB statement read.

Clark cited the number of teams with payrolls nowhere near the competitive balance tax threshold of $197 million as a reason for the union’s dissatisfaction with the winter.

“If teams aren’t competing, despite the fact that foundation for the system is such that every team is supposed to, that’s a problem,” Clark said. “And if it’s happening to the extreme that we’re seeing now and that’s the new norm, that’s a problem.”

RED SOX: Rafael Devers and Brock Holt hit RBI doubles to spark a three-run first inning, and Boston held on for a 4-3 spring training victory over Tampa Bay at Fort Myers, Florida.

RAYS: Top pitching prospect Brent Honeywell has a torn ulnar collateral ligament in his right arm and will have Tommy John surgery, sidelining him for the entire season.

REDS: The team signed left-handed pitcher Oliver Perez to a minor league contract. Perez had a 4.64 ERA in 33 innings with the Nationals last season.

TWINS: Minnesota signed 12-year veteran shortstop Erick Aybar to a minor league contract.