Actually, most of McVay's route combos do NOT include a mid-deep route this year and that's a huge part of the problem.
The offense was less efficient, but overall MUCH more productive and I think McVay has learned that when he tries to run this offense too efficiently, he removes some of the wiggle room you need with changing personnel and opponents.
There are many plays where NOTHING is happening further away than 10 yards, let alone 20. Defenses have focused on that, sat on the short routes or just played a short zone and put the DL in full rush mode.
Maybe switching to Wolford due to Goff's injury will be enough to get McVay to shake loose a bit.