MESA, Ariz. — The signs on the closed ticket windows at Sloan Park all read, “Game cancelled due to inclement weather.” But by Monday, it had been four days since rain was a factor for a baseball game in Arizona.

It was as if everybody just left and never came back when Major League Baseball shut down spring training last week. There were no signs or indications to suggest the coronavirus pandemic had caused it, or for how long. Just pushed-aside equipment, folded chairs, parked golf carts, empty fields and padlocks.

By Tuesday, even the skeleton crew of team officials the Cubs planned to keep in place to support players who chose to stay and work out on their own is expected to start clearing out — along with many of those players. That development followed MLB’s announcement Monday that a restart has been pushed back to mid-May at the earliest.

The announcement came after commissioner Rob Manfred’s conference call with all 30 teams Monday — a day after the CDC recommended that events involving 50 or more people be canceled or postponed for the next eight weeks. Last week, MLB shut down spring training and announced it would delay the start of the season until at least April 9.

With information regarding the spread of COVID-19 developing daily — even hourly — MLB offered nothing close to a target date for opening the 2020 season.

“We’re going to have to see how things develop,” Manfred told the St. Louis Post-Dispatch. He would not speculate on whether any games might be played without fans in attendance once the season begins.

Infielder Jason Kipnis, a Northbrook native in his first season with the Cubs, tweeted disappointment after Monday’s announcement: “I agree with every shutdown and safety precaution being taken . . . safety first . . . but this sucks even more cause all I’ve been waiting to do is play in front of a packed Wrigley. #oneday #whenthetimeisright”

Manfred also told reporters in Florida on Monday that MLB intends to play a full 162-game schedule in 2020, which seems unfeasible even if the season were to start by late May.

Meanwhile, various reports quoted unnamed executives familiar with the conference call as speculating that the season might not start until July.

The status of the Cubs-Cardinals series in London in June is at least doubtful at this point, and the All-Star Game in Los Angeles in mid-July also is in jeopardy.

Shortening the season creates layers of issues, from redrawing an equitable schedule to adjusting transaction deadlines, players’ service time and salaries — all of which must be negotiated with the players’ union.

MLB also is expected to announce a roster and transaction freeze this week, which would, among other things, delay any long-term extensions.

The Cubs and shortstop Javy Baez had been in negotiations about a possible extension.