Heh, ok.
Best individual passing season:
Grogan (1979): 206-423 (48.7%), 3,286 yds, 28 td, 20 int, 77.4 rating
Newton (2015): 296-495 (59.8%), 3,837 yds, 35 td, 10 int, 99.4 rating
Best individual rushing season:
Grogan (1978): 81 att, 539 yds, 6.7 avg, 5 td
Newton (2012): 127 att, 741 yds, 5.8 avg, 8 td
Career passing:
Grogan: 1,879-3,593 (52.3%), 26,886 yds, 182 td, 208 int, 69.6 rating
Newton: 2,371-3,980 (59.6%), 29,041 yds, 182 td, 108 int, 86.1 rating
Career rushing:
Grogan: 445 att, 2,176 yds, 4.9 avg, 35 td
Newton: 934 att, 4,806 yds, 5.1 avg, 58 td
Whether you take them at their peak, or over the course of their respective careers, there's literally nothing that Grogan did better than Newton. Newton is a better passer than Grogan was. He's a better runner than Grogan was. He produced WAY more touchdowns (Grogan 217 rush+pass TD, 13.6 per season; Newton 240 rush+pass TD, 26.7 per season). He turned the ball over way LESS.
Yes, Grogan played in a different era where it was harder to pass. That's why I asked if you wanted to look at AV, which adjusts for that. And if you use that metric, Newton's top 3 AV seasons were 2015 (20), 2011 (19), and 2012 (19). Grogan's top 3 AV seasons were 1978 (16), 1977 (15), and 1979 (14). Career AV: Newton 123 over 9 seasons (13.7 per season), Grogan 116 over 16 seasons (7.3 per season).
Newton was better at everything a QB is asked to do. Newton has been a 3x pro bowler, 1x all-pro, and 1x MVP. Grogan never even made a single pro bowl, never mind all-pro and of course never mind league MVP. At his best, Grogan doesn't stack up to Newton's best. And it pains me to say that because I loved Steve Grogan more than any other player besides Andre Tippett growing up.
But facts are facts. It's not even really particularly close.