1. They did find ways to get him on the field. But he didn't overtake DD or Werner.
2. Where is it reported that the Saints didn't offer more than the Eagles? You still can't refute the basic and self evidential truth that the player chose to try his luck elsewhere. Are you going to put a near-$20m tag on a rotational LB just to keep him?
3. So the coaching staff moved the player around in an attempt to find ways to get him on the field, as you demanded at the top of your post, and this actually contributed to him feeling uncertain about his abilities and deciding to go somewhere else? Oh, the irony! Maybe your blinding insight on point 1 isn't all that great after all.
I still think there is a reasonable debate to be had over whether, at the end of 2023, ZB was worth keeping based on future potential, meaning also deciding to ditch all pro LB and team leader DD. But if we're truthful with ourselves, rather than desperately rushing to berate the team over 'another former Saint that flourished elsewhere', that is a hard sell.