This has been discussed so many times and at least in the case of Quinn is totally not true. In two stints where he came back last year, he was outpacing his rookie year. Both. Times. This has zero to do with his injuries.
I believe it was @mjd1001, our resident Cozens scholar, that pointed out that Dear Mr. Cozens was playing like shite last year before he got his face caved in.
Both injuries are strawmen that avoid talking about why these two players cannot seem to remove their heads from their rectums (rectum? damn near killed 'im!) in a system that is more than just pond hockey.
It is also funny because Sabres fans tend to think Quinn is unique. High draft pick players fail to become impact player A LOT ... or take a while. That dude on the Rags, La Fran Yayr - no clue how to spell it - he was borderline awful his first 2-3 years. Then it clicked. Shane Wright on Seattle. This was the kid that was given "exceptional status" to play as an underager in juniors. He was talked about as a potential #1 pick ... he has like 4 points this year. Slafkovsky - #1 overall pick - 74 points in 144 games that is a 40 point pace for a full season.
I don't think any of those players are bad or busts or whatever, but they are not McJesus or Crosby or MacKinnon ... they are regular NHL players. 🤷♂️