We are talking about multiple teams who are competing against other teams for a player of need and each situation is different. I can’t judge Marte’s value if I don’t have all that information on me nor can you. This isn’t a value chart like a NFL draft trade or something. Your battling an unknown measure of each team’s willingness to go all in.
Marte and a few decent prospects could land Bart. Doesn’t matter if those prospects are ML ready either. It helps but it’s not a deal breaker for a team who in need of the main piece.