What Marvin and Richard bring to the table is not that valuable. According to basketball-reference, Marvin's PER is 14 and Richard's 12.6. To put that into perspective, Jeremy's is 17.6. League average is 15. Even if you replace them with the likes of Garret and Clarke, you get 16.3 combined PER. That's a decrease of 10 altogether. Does that really make us go from where we are no to Bucks level?
Please not that I'm in no way suggesting PER to be authoritative, I just wanted to use one of the numbers that attempts to measure a player's total contribution to his team.