Another good writeup detailing what the players want with respect to service time and getting players paid at younger ages:
https://www.mlbtraderumors.com/2021/12/collective-bargaining-issues-service-time-structure.html
Assuming Scherzer is representing the consensus: “unless this CBA completely addresses the competition (issues) and younger players getting paid, that’s the only way I’m going to put my name on it.”
So, get them money sooner, and eliminate teams tanking.
Players want "players to reach free agency after six years of service or after five years of service and 29.5 years of age", which is a fairly meaningless change. Since it's a non-starter for the owners, just drop it.
Instead, get a meaningful increase in the minimum salary, which can be compounded into higher arbitration salaries. Perhaps increase the minimum salary based on service time ($700k for rookie, additional $100k per year of service). That satisfies the goals of players getting paid sooner.
The competition issue is much more tricky. Getting teams to stop cutting payroll while rebuilding is going to be very hard, and the players may be barking up the wrong tree there.