I never said injuries in year 1 are an excuse, what I said is in year 1 he may deserve the benefit of the doubt, he hasn't established a pattern yet of suckage yet. Year 3 and Gannon has experienced ZERO success in his tenure, none, he does not deserve any leeway for injuries, he deserves to be unemployed. I don't care about injuries, I care about results and he is 20 games below .500 after 3 years! Again the Cardinals in their entire history have lost 13 games FIVE times---2 of those are under Gannon! The Cardinals have only given up 450 points or more in a season 3 times--2 of them were with Gannon as head coach! Defense is supposed to be his area of expertise and the team is awful on defense.
As for schemes, it doesn't matter if your situational play-calling is awful.
If he comes back we will still be stuck in 4th place again, with no hope in sight--that's about guaranteed. If we replace him, we will probably still be in 4th place next season but we MIGHT get lucky and make a great hire (like we did with Arians) and have a something to look forward to. Bringing Gannon back for year 4 just delays his inevitable firing by a season--sure we may slog from 3-14 to 7-10 or so, but big deal.