I went back to look for the poster that provided Groce's conference records at Ohio (was barely above .500) and Illinois (below .500). To me, this speaks volumes about the quality of coach that he is. FWIW, I really like him as a guy. I've met him multiple times, as I know many of you all have as well, and he couldn't be nicer. And there's no question that he's got a TON of passion for the program. However, that only goes so far.
IMO, a coach's record in conference play is one of, if not the single, best ways to judge their ability as a coach. That's because, I feel, winning conference games is significantly tougher than winning non-conference games. Your conference opponents know your offensive and defensive schemes as well as anyone in the country. There are two ways a great coach can overcome that. One is by having the ability to recruit superior talent. Clearly, that hasn't happened here. The second is having comparable talent but being able to make in-game adjustments to out-execute your opponent. I have seen ZERO examples of this in JG's 4 years. If you can't get better players and you can't create effective game plans and/or make necessary adjustments, you're not going to win.
For me, four years is a big enough sample size to know that JG is in over his head here. I think he'd make a fantastic lead recruiter for a team but isn't qualified to be a head coach in the Big Ten.