I think during the bye week they made some big changes. I know personally - even watching some games where they scored 40+ points earlier in the season, I still couldn't stand watching that inefficient offense that was just looking for big dagger plays even when they weren't there.
I cited some stats about Mike Evans last week, but his yards per target is at a ridiculous ~13.5 since the bye. And that's because most of his routes have been so much more efficient. He's running a lot of comebacks, curls, slants. Earlier in the year, it was all go routes, back shoulder stuff...just low percentage.
Godwin, Brown, and Miller are all getting the ball more efficiently in space rather than those over-the-top routes. They've also largely stopped trying to force the ball to the running backs since they aren't very good after the catch. And they've gotten Brate involved a lot more.
So yes, I agree. They had been running a very inefficient offense all year, but their success the last four games is not just due to inferior opponents, and the game against Washington was telling. I hated how stubborn they were for much of the season, but it's clear now that this offense is finally being influenced by Brady, hence these horizontal and middle of the field routes by Brown and Godwin, constant rotating different personnel in and out, pre-snap quick reads, etc.