When is the last time we've had a player "bloom" and become a star after patiently biding their time in the program for 3 or 4 years after redshirting???
2017 - Womack, Christian Miller, Anfrenee Jennings, and Anthony Averett all took redshirts and we big parts of the success this year. Holcombe was also a redshirt who was an early contributor in the season
three of those guys are back in 18, and add Deionte Thompson and Quinnen Williams as guys who'll be either starters or significant contributors.
in 17 we'd also would have liked to redshirt both Cowan and Allen and would have if not for the injuries so we'd continue the trend.
The staff typically talks with each player about this before they come in. Some certainly come in ready as you mentioned, but many come in knowing they're likely to redshirt, especially the DL, OL and OLB guys so they can get stronger/bigger. For some, they might be changing positions and need time to get used to that (also a lot of OLB guys since we recruit a lot of guys who play DE in HS to play OLB for us).
That said, point taken that a lot of guys, especially top rated guys, are coming in with an expectation to play early, and if they don't, they think about bolting.