ARLINGTON, Texas -- Hours into Major League Baseball's first work stoppage in 26 years, commissioner Rob Manfred said the union's proposal for greater free agency and wider salary arbitration would damage small-market teams.

Owners locked out players at 12:01 a.m. Thursday following the expiration of the sport's five-year collective bargaining agreement.

Since 1976, players can become free agents after six seasons of major league service. The Major League Baseball Players Association proposed starting with the 2023-24 offseason that it changes to six years or five years and age 30.5, with the age in the second option dropping to 29.5 starting in 2025-26.

MLB would keep existing provision or change eligibility to age 29.5.

"We already have teams in smaller markets that struggle to compete," Manfred said during a news conference at the Texas Rangers' ballpark, not far from the hotel where negotiations broke off. "Shortening the period of time that they can control players makes it even harder for them to compete. It's also bad for fans in those markets. The most negative reaction we have is when a player leaves via free agency, We don't see that -- making it earlier, available easier -- we don't see that as a positive."

Baseball is in its ninth work stoppage, threatening the start of spring training on Feb. 16 and Opening Day on March 31.

"The players' association, as is their right, made an aggressive set of proposals in May, and they have refused to budge from the core of those proposals," Manfred said. "Things like a shortened reserve period, a $100 million reduction in revenue sharing and salary arbitration for the whole two-year class are bad for the sport, bad for the fans and bad for competitive balance."

An agreement by early-to-mid-March is needed for a full season.

"Speculating about drop-dead deadlines at this point, not productive," Manfred said. "So I'm not going to do it."

Union head Tony Clark planned a news conference for later Thursday.

Negotiations have made little to no progress since they began last spring. Manfred said a lockout was management's only tool to speed the process.

"People need pressure sometimes to get to an agreement," Manfred said. "Candidly, we didn't feel that sense of pressure from the other side during the course of this week."

In many ways, the core of the dispute is over the union's desire to have more teams chasing players, leading to more competition on the field and higher salaries, and management's desire to restrain salaries in an effort to prevent high-revenue teams from gaining an even greater percentage of stars.

"I've watched this game as an insider for more than three decades," Manfred said. "I think that most people who understand the game realize that in our smaller markets, it's a lot harder to win than it is in our bigger markets."