There's reasons for players regressing.
Sometimes it's age.
Sometimes it's injuries.
Sometimes it is that they just didn't prepare as hard.
Sometimes they get a fat contract and then mentally retire.
Sometimes they are asked to do new things they can't.
Sometimes, especially on an oline, things are not in synch and the guy standing at the end of the line gets too much blame.
It's not unlike when a WR makes a mistake and stops short of where he's supposed to be, or turns in when he should have turned out, and the QB throws the ball to where the WR was supposed to be and boom. INT. But..... the INT is hung around the QBs neck and not the WRs like it should be.
So, I really don't know why Havs just didn't look the same last year. But there IS a reason. Has it been solved; is it not solvable? Don't know. Or...... are the new guys (like Evans) just flat better players?
I know this. McVay and his assistants will start the best players that gives the team the best chance to win; not guys they have fallen in love with or the guys with the big contracts. The proof is Gurley. He was benched for an aging vet that couldn't stick with other teams. Even in Championship games. Takes some guts to do that; but McVay was right to do it.