What I noticed from re-watching last season's finale was Negan is a classic bully. Acts all tough but down deep he is a coward. The way he screamed like a little girl when the tiger attacked and he saw Maggie.
Rick and company did have a major win last night, because they exposed even more cracks in Negan's following. We already know Dwight and Eugene are against him, the guy who collects from the Kingdom wavered. Gregory will do whatever it takes to save his own butt, and the garbage-pail kids can't be trusted. It is pretty much Negan and Simon vs everybody right now.
Doubt was created, Negan showed weakness, and he rules by fear...that spells trouble.