I mean - Belly just got $17M last year, coming off a horrendous 83 wRC+ season. Even if he does settle for some 1 year deal, it's almost assured it will be for more than $20M. Almost every team in baseball would want Belly for 1 year $20M this year. Even if he has to settle for a shorter team "prove it" deal, it's most likely to be a multi year deal with opt-outs. I could see something like a 4 year $80M deal with the first year being worth $30M - and there being opt-outs for Belly after year 1.
If Belly repeats the 5 WAR season, he takes his $30M and opts out - signing a big deal next winter. If he returns to a 2 WAR player (or flops) then the team is paying him $16.7M annually over the next 3 years - and there is some upside that he'll rebound and provide excess value for those remaining 3 years.