They tried that with Williams and it turns out the backups are somehow worse. The entire defensive problem comes down to 3 players not being able to cover. Marcus Williams just seemingly has no idea where to be on the field at any given time. The exemplar of this was on the deep to pass, to I believe Chase, where Stephens is, shockingly, in the correct position covering the underneath and Williams sees this and goes "I will also cover the short pass as there is no way Chase would go deep" and then a big play is immediately given up because not only was his angle awful but his decision making was as well.
The aforementioned Brandon Stephens is basically the target whenever a CB is being targeted. If I am supposed to believe it is a scheme problem then why is it that whoever Humphrey covers is always blanketed (if this defense was not terrible I would say he would make all pro this year and he still might), and even Wiggins looks decent in coverage, and great for a rookie. It is literally just Stephens that gets targeted every single game when you go to a corner.
Meanwhile over the middle it seems like Roquan has basically just gotten lost covering people. His pass coverage has been abysmal. He loses the RB, he loses the TE, and just seems to always be a little behind which is odd because it is out of character but its clearly him not playing well and they cannot actually replace him.
That is the reason I am tempted to believe it is a "play better" bit of logic. Humphrey and Hamilton still look great, and even the role players are looking good (sometimes better than expected). It is literally just those 3 that just seem to fall apart in coverage.