No it really shouldn't be better. Meyers was the best WR on the team. He is gone. Harris was one of the top two RB's. He is gone. The other RB in Stevenson has been a huge downgrade. The replacement WR in Juju has been a huge downgrade. The offensive line is at the bottom of the league. You want to see what an extremely bad offensive line does to a great QB, look at Patrick Mahomes in Super Bowl 55. Dude fought like a hero and still had the worst game of his career and got trounced badly AND he actually had great players to pass to.
There was absolutely zero reason to think this offense was going to better than last year unless you bought into the hype of BOB being some magic fix all. BOB maybe can run a good offense when prime Brady, Gronk, Welker, Hernandez, Ridley, Green Ellis, Vereen, Woodhead, Mankins, Vollmer, Light, Solder, Cannon and Connoly on it. But this ain't it and it never was.
Yeah Mac has not developed. That's on the team though. This fanbase used to mock the Jets for years for doing similar to their QB's. And this about as bad as I've ever seen the Jets do it. People just want a conveniant excuse because they can't blame the organization because then they have to face the depths of the problems.
And that's just the offense. Let's be real, the special teams is near the botom of the league right now and the defense despite a decent game against a crap Colts team has routinely been bottom third. It's a total failure across the board.
Yes the QB is near the bottom of the league. The offensive line is in fact worse by virtually every metric. This is one of the bottom tier WR sets in terms of production and separation. The RB's are near the bottom of the league in terms of production. Aside from run stopping the defense is sub 20th ranked in virtually every stat. The special teams has consistently been hovering between worst and bottom three since the start of the year. It's just insane to look at all that and blame the QB.
As far as development, you can look at how every great QB ended up developing. The Patriots simply have not done that for their QB. It's not a surprise what the result was. It's easier to blame one guy over the whole organization.