I would argue it is not a decline but more so defenses caught on what they needed to do. When teams started to play cover 2 high shell it correlates with declining RW stats. Mentally RW should know that if it is a cover 2 high shell you check in at the line. And you auidible to go for quick slants, run up the gut or a quick pass up the seem with a TE. Basically it becomes pitch and catch until the defense decides to come out of the cover 2 shell. Brett Favre used to do this all the time against the Tampa Bay Buccaneers when they went to cover 2 or tampa 2 coverage.
With his decline of running(Sandlot)his way out of this coverage..You are correct on what a QB should do
However
Me3 is not that kind of QB..
He hates the pocket,cannot process fast,doesn't do audibles or pass to short unless it's a shovel to RB.
Seam route would work when he can see it but that means moving out for him to do it by that time he's
usually taken too long and sacked.
This why the his legs being gone are a big deal..That was his his game without that he's become even more limited.
You will still see a nice deep ball occasionally if a team like the Jags is stupid not to use cover 2 high
but even his deep ball is starting to go(arm) I've been observing him under throw since last season
before the injury and that's why I've been saying he is aging faster than typical.
Then again he played lots of baseball and has thrown tons over the years so maybe the arm is starting
to say it's had enough.