There's no agreement between Major League Baseball and the Players Association, and there never was one. Not a completed one, anyway.
It's essential to know this before delving any deeper into how dumb it'd be for both sides to blow up a 2020 season.
On March 26, a couple weeks into the coronavirus crisis, MLB and the union signed an agreement that called for players to be paid a pro-rated share of their regular salaries in the event of a shortened season. The players snapped it up. Hands were figuratively shaken. The camaraderie was hailed in headlines across the sports world.
So when MLB and the union resumed a couple weeks ago setting the stage for the actual return of baseball, and MLB used its national media surrogates to broach the subject of splitting revenues 50/50, now that it was clear fans won't be allowed inside ballparks ... boom went the dynamite.