Del Neri had frozen out Cassano for several weeks after a training ground row, but since his recall, the striker has been impressive.
Speaking with Gazzetta dello Sport, Del Neri was asked if it was courageous of him to drop Cassano.
"No, because before I took the decision I thought about it 100 times. We had a problem in attack. We needed more substance and less technique, Pozzi instead of Cassano, someone who helped the team move up the pitch, someone who pressed the opponent.
"Now, things are going better, even if it's not ideal. But in one move of his during the derby I saw the right level of anger. He'll be great when he can move like that more.
"Before Cassano couldn't manage many 30m sprints. When he plays further forward he has to sprint 10m so it's different. The question is: when will he do 30 separate 10m sprints?
When asked if he would do the same with Ronaldinho and put him in the centre of the attack, Del Neri said: "Ronaldinho is better than Cassano when he starts with the goal in front of him and a little bit of space.
"Antonio is stronger in the area with his back to goal. But Milan have many champions, not just Ronaldinho."