So would you say Robert Quinn was productive?
More productive than the three DEs who are remaining on the team? Yes.
You are going with the big stat for defensive linemen, the sack. That is a major disservice to the position. Consider Quinn sack production last year. It was a career year for Quinn. Consider that his career year in sacks was around one sack per game.
Are you going to tell me that a DE who is effective once per game is doing a good job?
I would hope not. What made his 2021 a good year was the career year in sacks, good production as a rush defender, QB hits, QB hurries, QB knockdowns, pass breakups and turnovers.
Have you ever heard that a QB hurry is almost as good as a sack?
The reason for this is both help the DBs who are covering WRs, TEs and RBs to not have to cover them forever. Given enough time, no CB can cover even backup WRs because they will eventually be open.