Agent Brodie Van Wagenen of Creative Artists Agency stopped short of using the word "collusion" but said the behavior of owners "feels coordinated, rightly or wrongly."
"There is a rising tide among players for radical change," Van Wagenen said in a Twitter post Friday. "A fight is brewing. And it may begin with one, maybe two, and perhaps 1,200 willing to follow. A boycott of spring training may be a starting point, if behavior doesn't change.
"Bottom line, the players are upset. No, they are outraged. Players in the midst of long-term contracts are as frustrated as those still seeking employment. Their voices are getting louder and they are uniting in a way not seen since 1994."
Players did discuss the possibility of boycotting the first days of spring training in a conference call last week, sources told ESPN's Buster Olney, but baseball industry sources indicate it is not currently an option under serious consideration.
The Major League Baseball Players Association confirmed Sunday in a statement that no spring training boycott was being threatened.
"Recent press reports have erroneously suggested that the Players Association has threatened a 'boycott' of spring training. Those reports are false. No such threat has been made, nor has the union recommended such a course of action," the union said.
Commissioner Rob Manfred, addressing the slow hot stove market at the quarterly owners meetings in Beverly Hills, California, on Thursday, cited a number of factors that have contributed to the lack of activity this winter.
"Every [free-agent] market is different," Manfred told reporters. "There's different players, different quality of players, different GMs, different decisions, a new basic agreement, different agents who had particular prominence in a particular market in terms of who they represent.
"Those factors, and probably others that I can't tick off the top of my head, have combined to produce a particular market this year. Just like there's been some markets where the lid got blown off in terms of player salary growth, occasionally you're going to have some that are not quite as robust."
Although MLB declined to respond to Van Wagenen's statement directly, the commissioner's office has said privately that a spring training boycott would be a violation of baseball's collective bargaining agreement.
Van Wagenen represents such prominent players as Ryan Zimmerman, Robinson Cano, Jacob deGrom, Yoenis Cespedes and Ian Desmond. The CAA group also represents current free agents Todd Frazier, Andrew Cashner, Jon Jay, Jason Vargas, Chris Young and Matt Belisle — all of whom remain unsigned.
Van Wagenen joins Scott Boras as the second high-profile agent to publicly question the lack of activity in a dormant winter for baseball free agency. Outfielder Lorenzo Cain's five-year, $80 million contract with the Milwaukee Brewers is the most lucrative deal of the offseason. Meanwhile, Yu Darvish, Jake Arrieta, J.D. Martinez, Eric Hosmer, Mike Moustakas, Lance Lynn and Alex Cobb are among dozens of free agents still looking for work.
More than 90 players from this year's initial free-agent crop are still unsigned, according to the Major League Baseball Players Association.
"Many club presidents and general managers with whom we negotiate are frustrated with the lack of funds to sign the plethora of good players still available, raising further suspicion of institutional influence over the spending," Van Wagenen said in his statement. "Even the algorithms that have helped determine player salaries in recent years are suggesting dramatically higher values than owners are willing to spend."
At a charity luncheon in Boston on Friday, Red Sox president of baseball operations Dave Dombrowski said he has never seen an offseason as slow as this one.
"This is by far the most unusual situation," Dombrowski reportedly said. "You usually have a player or two who might be out there in a particular year, but never the number of free agents that we have.
Dombrowski was filling in on a panel for Boras, who reportedly canceled his scheduled appearance at the luncheon, which benefited Paul and Theo Epstein's Foundation to Be Named Later and the Red Sox Foundation. Boras represents some of the most high-profile agents who have not yet signed, including outfielder Martinez.
Red Sox president Sam Kennedy acknowledged the inactive free-agent market has "somewhat" hurt business for the team.
Kennedy said that ticket sales are down "a few percentage points" from the same time last year. He said he figured it would pick up when the Patriots season ends and if the Red Sox sign a big name.
Rhetoric from the players' side has grown increasingly more combative as spring training approaches. Los Angeles Dodgers closer Kenley Jansen told reporters, "Maybe we need to go on strike, to be honest with you," during the team's recent fan festival. Van Wagenen, similarly, said owners are testing the players' resolve with their lack of offseason spending.
"I would suggest that testing the will of 1,200 alpha males at the pinnacle of their profession is not a good strategy for 30 men who are bound by a much smaller fraternity," Van Wagenen said in his post. "These 1,200 players have learned first-hand that battles are won through teamwork, and they understand that championships can't be achieved by individuals. They are won by a group united by a singular focus. Victory at all costs. They are willing to sweat for it; they are willing to sacrifice for it; they are willing to cry for it; and most importantly, they are willing to bleed for it."
In a statement on Friday afternoon, MLB Players Association executive director Tony Clark said players will continue to defend themselves if "attacked."
Baseball has not had a work stoppage since 1994-95, when the owners' threats to impose a salary cap prompted players to go on strike in August 1994. After then-commissioner Bud Selig canceled the World Series, the dispute was settled in late April 1995, and MLB has enjoyed a run of labor peace in the 23 years since.