Del Neri had said that Cassano would not return for several weeks after recovering from a muscular problem and since he was frozen out as a tactical measure, but made his first appearance since January.
The coach said: "Antonio will rediscover his form by playing portions of games. He is working to get back to full fitness and that makes everyone happy.
"Antonio is an important player, but he remains part of a team. It's crucial that there are precise definitions, that if he gives us a hand then we will help him.
"Even if it could hurt, recently we have been very clear in our positions. In my view it is better to be clear.
"The important thing is that he understands the way we think. This is why I confide in Cassano for this final rush of the season that could take us to unthinkable heights when we started out."