Kenny was always going to need time to develop and help in the NFL to consistently take his team to the playoffs. Starting his career as a game manager was correct in theory, but awful in practice.
1. The Steelers didn't have a good offensive line in place for a young QB. Bad offensive lines ruin borderline QB prospects all the time. He clearly doesn't trust the line.
2. A good ground game could've taken pressure off Pickett. Instead, they had him throwing a ton early in his career.
3. When you draft a young QB, teams should have a great QB coach or OC. The Steelers have neither and Canada is probably the worst qualified OC in the NFL.
4. The philosophy is predicated entirely on not making mistakes. This limits the throws the QB will make and completely changes the mindset.
I was worried the Steelers wouldn't be the right team to develop Pickett based on the last two years of offensive football we saw with Roethlisberger. It's a very QB unfriendly offense and that has proven to be the case with Ben, Mason, Mitch, and Kenny. A coach like Sean Payton or another offensive guru would've been perfect to develop Pickett.
That isn't saying Pickett has brought a lot of the problems on himself--he has a lot of those. I just don't think the Steelers coaching staff put him in the best position to succeed.