A few people were hyping Johnson but I don't think anyone thought he was the next Kelce or Kittle. Johnson showed flashes, but he's inconsistent as a pass cathcher and has never really developed as a blocker. He also fit better into the old scheme. He lacks the blocking skills to really fit into what Kubiak is doing with the TEs. But, a lot of that is that all the TEs are being kept in to block or chip which means they aren't going to get much in the way of opportunities int the passing game. Especially considering how much we run the ball.
As far as Perry, I think he got over hyped on a very small sample size last year. He made some plays but he didn't consistently show up and if you are going to get playing time, you have to consistently show up. That's especially true because the way Kubiak runs the offense, the 3rd WR doesn't get many snaps and very few targets in during those snaps. In the Payton offense we ran a lot of 3, 4 and even 5 WR sets so there were a lot more opportunities and it wasn't as important to play consistently because there were more opportunites.
There is also the fact that Perry keeps showing up on the injury report with a hand or hamstring injury.