Let's keep this broad, for now...and let's take aside the QB position altogether.
This was a team that was built over the course of three years to try and win games within an Adam Gase offense and a Matt Burke defense. The front office attempted to specialize the roster in order to accomplish that. Just because they ultimately failed to produce a winning roster, does not mean they failed to specialize the personnel.
On defense, we are switching from a Matt Burke defense to a Brian Flores/Bill Belichick defense. It is a MASSIVE change, at multiple levels of the defense. I suppose it's theoretically possible to make a bigger switch. But it's hard to fathom it happening in real life.
On offense, there's a switch from Mike Martz offense, that had some shades of Josh McDaniels added into it (mostly the use of No Huddle and Hurry Up, which never really caught on in Miami anyway)...to being more of a straight up Josh McDaniels offense centered on the Erhardt-Perkins way of teaching/structuring the play calls. This is a pretty average system change. It shouldn't be considered particularly easy, nor particularly difficult (unlike the defensive switch). What probably exacerbates the switch is the signaling that the team is going to switch to a run-oriented/power/play-action attack. That was very NOT Adam Gase.
In order to lubricate these significant system changes, they drafted/signed....who again? Christian Wilkins and a bunch of scratch-off tickets?
They have the lowest cash payroll in the NFL this year. They did not acquire a load of new personnel in order to try and facilitate the system switches.
On offense, it seems very likely that most of the "starters" at the skill positions (3 WR, 1 RB, 1 TE), as well as 4 of the 5 linemen, will be holdovers from the previous regime. And on defense, it seems very likely that 9 of the 11 starters will be holdovers as well.
The newcomers on both sides are mostly rookies (Michael Deiter, Christian Wilkins). Pretty much only two veterans (Dwayne Allen and Eric Rowe) were acquired specifically because their experience level should facilitate the system switches, and neither would be expected to be starters anywhere else.
There's either going to be a serious misfit problem between personnel and system, or there are going to be a bunch of semi-pro caliber players getting real snaps. That's where this is heading. And yeah that kind of does feel like the profile of a team that goes 3-13.
First, I 'liked' your post. So, based on your post, I agree. I do want to point out a few things - uncertain if we agree or not.
First, Miami jettisoned a QB who seemed unable to read Ds or set protections. RF is better at both. Rosen is unknown.
The D dumped the wide 9. Burke is gone. Those need no further discussion.
I lost count of the number of times, even late in season, when the D seemed confused in their assignments. Guys pointing in opposite directions. A receiver wide open and the closest defender was a concession guy, meanwhile 2-3 defenders on one guy.
O was no better. Was there a quarter when the D DIDN'T have an unblocked rusher? Would any HS coach put Gesicki one-on-one against the D's best pass rusher? Would any HS coach play soft coverage on 3rd and 2? How many sweeps did fans see on 3rd and 1?
My point is, while I agree on the personnel side, I can see improvement for no other reason than I expect players to know their assignments. I expect more cerebral QB play. I expect play-calling on both sides of the ball to be better. Now, I must add, a number of these 'improvements' I see are not guaranteed and based on how inept Gase and circus were. Gase won 7 with a keystone-cops outfit. I don't see 4 wins as difficult unless Flores is Gase's evil twin.