Defensively, last year's Giants were 13th in yards per game (15th against the pass, 14th versus the run), 30th in points per game, tied for 22nd in takeaways, and 21st in sacks.
Their ranks in those categories under Fewell this season: First (second, second), 12th, tied for second, and tied for 27th.
The only place Fewell hasn't made a difference is sacks accumulated. Everything else has changed significantly for the better since last season.
All things considered, Fewell did a pretty damn good job as the head coach here.