andy Dalton spent most of his career as a consistently above average quarterback. He's no superstar, but he would stabilize the QB position with consistently acceptable performances.
If I'm trying to gameplan an offense, I would 5000 times rather have a limited but consistent performance from my QB and a set of skills I could rely on working most of the time, than a flashy guy who can make big plays but can't do it consistently.
This is also the reason I suspect that Lamar Jackson is going to end up being something of a flash in the pan.