This nails it. If we could "replace" one position for an upgrade it wouldn't likely help all that much on a skill position, outside of maybe Gronk. The loss of Andrews has hurt tremendously. It's been a cumulative effect of Gronk, the line, and Develin.
It's not been one thing; it's been the accumulation of a bunch of things.
1. The loss of Andrews. Enormous. He holds all the keys to protection and blocking. As it turns out, he's a GREAT center. Karras has been better than Ferentz, but the drop-off from Andrews to Karras has been huge.
2. The loss of Develin. The best blocking FB in the league, he just is a wrecking ball out there. They have simply not been able to replace him or what he brings to the table. Roberts, ironically, is starting to get it, and as he's improved, the running game has improved too. But for most of the season, this was just a glaring glaring hole.
3. The loss of Trent Brown. This had to happen, as he was commanding a ridiculous salary, but we forget just how good he was last year. An absolute monster at LT. Wynn is, and will be, a pretty solid LT in the league for many years, but he's not yet at the level that Brown was at last year.
4. The health of Cannon and Mason. Those guys each suffered through stretches where they were either OUT or really banged up. It affected their play in a noticeable fashion. Both guys, when healthy and playing at their best, are pro-bowl caliber offensive linemen, but they haven't been close to that this year. Some of it is the health, and some of it is Andrews-related, with Mason having to help cover for Karras, leaving Cannon with no help on the outside. Given his sketchy health, leaving him on an island just hasn't been good.
5. The loss of Gronkowski. He wasn't GRONK last year, but he was still really good. And the best blocking TE we've seen in the NFL in a long time. His mere presence opens things up for other players as he commands so much attention. The drop-off from Gronk to Watson/Lacosse is just off the charts in magnitude.
6. The loss of Gordon and Thomas. Maybe these seem like smaller deals, but they were going into the season pretty stacked at WR. They traded Thomas when it was clear that AB was available. Then they got rid of Gordon when he became unreliable. Obviously Gordon is out of the NFL right now so that was prescient, but still...they don't have another WR as good as him. Thomas was a sneaky bad loss, as he brought a solid veteran presence at WR. Not the biggest loss, but it all adds up.
7. The injury to Harry. Really slowed his development. I think he's gonna be a good NFL WR when all is said and done, and clearly they're integrating him more and more, but they were hoping he'd be further along NOW than he is. The injury set him back.
8. The health of Edelman. Huge. Enormous. The guy is an absolute warrior, but he's clearly not EDELMAN right now. Even with Gronk, Edelman was the one who made it all go.
9. The decline of Brady. It's real. He's not declined into "awful" status or anything, but he's also clearly not peak TOM BRADY. Clearly. There's just no arguing with it, as much as some people might want to. Peak Tom Brady would have been putting up 27 points a game even with all they lost. He can't do that now and needs more help.
10. The kicking problems. Folk has done well, but before that, they were really really really struggling at K. Just giving away points in so many games, it was troublesome.
11. The decline of the defense. They started out like a house of fire, putting up record-setting numbers. Then things got real, and the defense slowed down. It's still "good", but the last 8 weeks have seen a marked drop-off in performance. With that has come fewer turnovers generated, and more first downs and yardage allowed, which has meant that the offense has had to work harder to score points - getting fewer opportunities (as teams have held the ball more), and worse field position.
So it's been a whole lot of things contributing to the team's problems. And yet here we are at 12-4 hosting a playoff game. There are worse situations to be in, and there's hope for improvement next year as some of these things will likely be better.