It’s not so much that the Bucks will miss Middleton’s 18–20 points a game (they will). It’s not that they’ll miss his spacing on a team that starts 3 non-shooters (they will). It’s not that they’ll miss his team and individual defense (they will). But the Bucks are going to have a really hard time filling that 36 minutes.
Basic counting stats as well as numbers like RPM or VORP tell you Middleton is a very good player. One of the best shooting guards in the league without question. And it’s easy to look at those numbers and say “man it will suck without him.” But to measure losses like this you’ve got to focus on the trickle-down effect on the depth.