Head smashing was also present enough in episode 5x09 to give us reason to believe Negan is around. When Noah found his old house, he found his mother with her head smashed in the living room. Very similar to what Negan did to Glenn.
A trade-off is a situation where you make a compromise between two things, or where you exchange all or part of one thing for another. ...the trade-off between inflation and unemployment. American English: trade-off
In economics, the term trade-off is often expressed as an opportunity cost, which is the most preferred possible alternative. A trade-off involves a sacrifice that must be made to get a certain product or experience. A person gives up the opportunity to buy 'good B,' because they want to buy 'good A' instead.