JUPITER, Fla. — For over five hours here on Monday, several of the most important people in baseball gathered at Roger Dean Stadium, the spring training home of the St. Louis Cardinals and the Miami Marlins.

Spring training, which was supposed to begin last week, hasn’t started yet because Major League Baseball locked out the players on Dec. 2 and a new labor deal has yet to be reached. An on-time start to the 2022 regular season — scheduled for March 31 — hangs in the balance.

Sensing increased urgency, the sides agreed to gather in Florida this week — perhaps all week should the talks prove productive — starting on Monday. Although M.L.B. made incremental moves in the players’ direction and many hurdles remain, the sides noted how helpful it was to talk face to face and agreed to meet again on Tuesday.

M.L.B.’s latest proposal included relatively modest tweaks on two matters: increasing the size of the bonus pool for players who are not yet eligible for arbitration (from $15 million to $20 million for 30 players) and upping the number of amateur draft picks to be determined by a lottery (from the top three to the top four). The union has proposed a bonus pool of $115 million for 150 players and a draft lottery for the top eight picks.

Among the other key areas in which there are sizable gaps: league minimum salaries, the luxury tax and its penalties, the revenue sharing system among clubs and the number of players eligible for salary arbitration. M.L.B. has repeatedly insisted it will not touch the last two items, both of which the union has sought to alter or expand.

On Monday, the sides met for hours but caucused among themselves for longer. Not only were the bargaining teams for M.L.B. and the players’ union present, but so were 10 players and two club owners. The owners were Dick Monfort, of the Colorado Rockies, and Ron Fowler, of the San Diego Padres. Monfort is the chair of M.L.B.’s labor committee and Fowler is a former chair.

The players in attendance, all of whom hold leadership positions in the union: Max Scherzer, Francisco Lindor and Brandon Nimmo of the Mets; Jameson Taillon of the Yankees, Brent Suter of the Milwaukee Brewers, Whit Merrifield of the Kansas City Royals, Sonny Gray of the Cincinnati Reds, Taylor Rogers of the Minnesota Twins, Paul Goldschmidt of the Cardinals and Jason Castro of the Houston Astros. Other players joined the union’s internal side sessions via Zoom.

Although several recent bargaining sessions were held in New York, where both M.L.B. and the union are headquartered, these talks were moved elsewhere. M.L.B. accommodated the union’s request to meet in Florida, where a large number of players live in the off-season.

A potential week of talks in New York would have made it harder for players to continue their workouts, hitting and throwing. And because the arrangements were finalized late last week and Monday was a holiday, a hotel couldn’t be secured for the negotiating sessions. So the sides turned to the meeting spaces at the unused Roger Dean Stadium.

Before the first meeting indoors at 1 p.m. on Monday, union officials and players huddled in a stadium parking lot. Throughout the afternoon, as many as two dozen fans or autograph seekers stood outside the gates. Two arrived with a sign that read, “We want baseball!”

Overall, the union has been seeking a series of improvements to the economic structure of the sport, with a goal of helping younger players, improving competition among teams, curbing service time manipulation and injecting more spending. The league, though, believes that players have a fair system without a hard salary cap and sees it as a matter of wealth distribution — that star players are disproportionately commanding more than others.

If the sides want to avoid altering the regular-season schedule, this week might be critical.

On Friday, M.L.B. announced the start of spring training games, originally slated for Feb. 26, was postponed “until no earlier” than March 5. Earlier this month, M.L.B. Commissioner Rob Manfred said losing regular-season games would be “disastrous” for the industry.

He also suggested that a minimum spring training length of four weeks — two weeks shorter than normal — made sense to avoid a spike in injuries, like the one before the pandemic-shortened 2020 regular season. As a result, M.L.B.’s stated preference for reaching a new collective bargaining agreement is Feb. 28.