I don't think he's regressed. I just think he peaked and plateued two years ago. He's every bit the 3* QB we thought he was. I think it's more of an indictment that ND couldn't manage to land and develop a better option over the past three years than what Book can/can't do by now.
Sent from my Pixel 4 XL using Tapatalk
Also, you see Ohio State/Georgia/Alabama/Oklahoma/etc. aggressively pursue transfers. ND doesn't do that. Kelly has yet to recruit an elite QB in 10 years, or find another way to get one on the roster. Sure, many of them are rated as "elite," but they're not even close to as good as their rankings. Book is at least exceeding his ranking, which is a rarity.
IMO, ND's problem isn't development... most of the guys look their BEST here and then look much worse when they move on... it's talent identification.
'11 -- Golson. Inconsistent, undersized. Did worse at FSU.
'12 -- Kiel. Transferred after he couldn't win starting job. Was OK at Cincinnati, had off-the-field issues there and did not make the NFL.
'13 -- Zaire. Had his only successful plays at ND, failed at Florida.
'14 -- Kizer. Played well enough in Kelly's offense to get drafted in the 2nd round, then washed out of the NFL.
'15 -- Wimbush. Inaccurate passer, lost his job to Book. Got beat out by a bad QB at Central Florida and did not make it to the NFL.
'16 -- Ian Book. Current starter, physically limited, likely to be a UDFA or late round NFL draft pick.
'17 -- Avery Davis. Position switch.
'18 -- Jurkovec. This is one to follow, because we don't know what he will or won't do at BC.
'19 -- Clark. Unknown.
'20 -- Pyne. Unknown.
On that list, I don't see a single one where there was a "development" issue. The so-called regression seems to be more that Kelly puts lipstick on a pig which makes them look artificially better than they are until opponents learn how to attack their weaknesses. For example, Ian Book torched teams for a couple weeks... now teams basically dare him to throw deep and try to sit on the short and intermediate stuff, and they also try to force him to stay in the pocket.
TLDR: I think the bigger issue is the players being recruited rather than the development of the players once they get here. There are very few players you can point to and say "that guy would've been a stud with better coaching!"