You touched on several things.
One they do have some oline issues.
One Reid is no longer calling the offense. I don't know why. But the guy calling plays is not using their weapons correctly. For example, T. Hill does one of two things, he runs a deep route or he's used as a decoy on a fake end around. Hill is a good receiver and a good route runner, they need to use him more as a complete receiver.
Same thing with Kelce. Kelce is a great TE but he's not going to run over a lot of tacklers, he's going to run past them. But instead of having him work between the hashes, they are using him as a blocker or trying that stupid shovel pass when he's right behind the center. But they need to start him off between the hashes and then have him do the double move to the outside.
They take Hunt out on most passing downs now. He is not as good a blocker as West, so that is part of the reason. But the defense has been so bad lately, that they have to abandon consistently running the ball.
Defensively. D. Johnson is not the sideline to sideline player he used to be, so the run defense is not as good. Sorenson is not as good in coverage as Berry and Berry was able to cover up some of the weakness at any CB not named Peters. And now Peters is still great in coverage but he doesn't want to tackle any more, he only tries to strip the ball and it leads to a lot of extra yards by the receiver.