I always think about John Wooden when I think about this topic. He says in one of his books that the best job coaching he ever did was for a 500 team. It's not about the record. It's about performing up to reasonable expectations.
You definitely want to see an upward trend. You want to see players playing hard, and things organized, and teams getting younger and deeper. And then you want to see game day competence.
For my part, Garrett is weak on the last bit, but has been strong elsewhere. We haven't trended up or down in his tenure, but I think as I've said elsewhere that the reasons for that have less to do with coaching than they had to do with other circumstances surrounding the team.
Campo, on the other hand was weak on game days. But he was also weak organizationally, could not handle Jerry, represented the team poorly, didn't ever have enough respect from the players and was eaten alive by the media. Plus he lost three more games each season than Garrett has. As I said, the two are not similar.