Well, just go ahead and think the worst, and formulate any scenarios you can to defend it. I'm sure you investigated him and found out that 95% of the passes thrown in his coverage were dump downs.

He hasn't always been only a bench player either for that matter. A part-time starter would better describe him. It's not like he only played defense late in blowout losses.
Even though the Jets weren't overall good teams, it seems the defenses were still good enough to win more if the offense had done their share.
They ranked 20th, 12th, and 4th in the last three seasons.
I'm sure you checked who the starting safeties were that he was stuck behind and concluded they weren't any good and if Davis was, he should have beaten them out.
I honestly don't know how well Davis will perform for us. I liked him at Cal and was hoping we'd draft him in 2020.
The Jets drafted him two picks before we picked Brandon Jones. Of course, we may well have still taken Jones even if Davis was on the board.
I figure the pro scouts employed by the Dolphins, (and all the other teams), watch tons of tape on all these guys and are able to extrapolate the individual players' strengths and weaknesses irrespective of the quality of the players around them. So, until we see how he performs for the Dolphins, I prefer to see the glass as half full.
Life is too short to dwell on constant negativity. YMMV.