Perhaps the BEST B1G Forum anywhere, here at College Football Fan Site, CFB51!!!

Player A
Year 1:  259-395 (65.6%) for 3,896 yds and 34 TD with 12 INT ~ 170.8 rating.......rush N/A
Year 2:  287-503 (57.1%) for 3,402 yds and 22 TD with 17 INT ~ 121.5 rating.......rush N/A
.
Player B
Year 1:  90-152 (59.2%) for 1,840 yds and 12 TD with 5 INT ~ 180.4 rating.....108 car for 585 yds rushing (5.4 ypc) with 8 TD
Year 2:  87-161 (54.0%) for 1,234 yds and 8 TD with 6 INT ~ 127.4 rating.....104 car for 617 yds rushing (5.9 ypc) with 8 TD
.
Player C
Year 1:  107-161 (66.5%) for 1,474 yds and 7 TD with 6 INT ~ 150.3 rating.....156 car for 418 rushing yds (2.7 ypc) with 8 TD
Year 2:  119-204 (58.3%) for 1,131 yds and 4 TD with 10 INT ~ 101.6 rating.....104 car for -1 rushing yard (0.0 ypc) with 2 TD
.
Who fell off the biggest cliff?  Player IDs after voting concludes.

A

Player C went from useful dual-threat production to basically losing the entire rushing side:

418 rushing yards and 8 rushing TDs down to -1 rushing yard and 2 rushing TDs. Add the passing drop and the higher INTs, and that’s the biggest all-around collapse.
So my ranking would be:

1. Player C - worst overall regression
2. Player A - worst pure passing/volume regression
3. Player B - ugly passing drop, but rushing softened the fall

C is the worst regression (and I think I might remember who it was and be laughing about his pro prospects?)

B feels like an option QB who dipped slightly with some noise. EDIT: I now have a guess for B and it’s not a pure option guy, but more of a modern one.

A feels like a gunslinger who got overconfident and sloppy (I also think I know who that was)

And wrong on all guesses!

Could you share your guesses? (not the actual players)
I'm curious who you were thinking. 

My thoughts--guess since everyone is talking reasoning I might as well add my own...

A: Drop-off on every statistical measure, comp%, ypc, ypa, TD/INT. But this to me is perhaps a team that got worse around the player, and he was asked to contribute a lot more volume. I don't worry about the raw INT numbers, because it's on almost 25% higher volume. And I don't necessarily worry about raw TD numbers, because depending on system teams can punch it in on the ground. I recall one year Curtis Painter at Purdue had a pretty bad TD:INT ratio, but that was when the team was running some spread option and RB Kory Sheets had a massive year for rushing TDs. They schemed the ball to the RB in the red zone so the lack of TDs wasn't Painter's fault. So to me this is a player that was just asked to do SO much more and statistically suffered because the team around him wasn't as good. 

B: Dual threat QB that ultimately isn't exactly a volume passer to begin with. Took a statistical step back throwing the ball in year 2, but not massively. Had greater than 10 ypa in year 1 and greater than 10 ypc in year 2, so this wasn't a "dink and dunk" passing game. So I'm not going to penalize one additional INT on slightly higher volume, and much like player A, a few fewer passing TDs is statistical noise. The rushing didn't fall off, so to me this player didn't regress all that much at all. 

C: First year under 10 ypa and second year nearly down to 5 ypa, so this team wasn't throwing deep all the time. At 5 ypa, under 60% completion with 10 interceptions (almost 1 in every 20 attempts) is pretty terrible. Significant statistical drop-off in pretty much every measure in the passing game. Rushing also fell off a cliff, so he wasn't adding value with his legs. Perhaps some of that was due to taking sacks which count against rushing yards, but it's still pretty bad.

So I had to vote C.

Yeah, the 17 INT's tipped player A in for me.

17 is too many.