I've got no inside information. It's just my opinion.
We've got three formerly solid guys (Solder, Vollmer & Cannon) and one formerly OK guy (Connolly) regressing badly, a rookie (albeit a late rounder) who didn't make it out of camp and hasn't even gotten a sniff on anyone's practice squad. And very little in the way of bright spots. Pass protection sucks, run blocking sucks, hell..even our screen game sucks because D-linemen are getting in the way of it or tackling the receiver instantly. I just saw a graphic on ESPN, we've got the 23rd best offense and Brady has taken more hit over the first three games than any time in his career (11 more than last year).
I forget the name of the phenomenon, but many (many) years ago, in a business class, I learned that when you've got that many individuals in the same department (or line or unit) screwing up at the exact same time, it rarely is the fault of the individuals. It's not a co-incidence. Several people don't usually screw up in the exact same way at the exact same time. If that happens it's systemic; it's higher up the chain. And since the only new coach on the team is the O-line coach, for me, that narrows it way down.
If say, a few guys sucked, but a few guys looked pretty good, or pass protection sucked but run blocking showed promise (or vice-versa) or any bright spots, however inconsistent, we could say "It's a new system, they'll get it with a little more time". But this is by far the worst O-line of the BB era, with little-to-no improvements from week-to-week, and a dearth of bright spots to hang our hat on.