Averages since 2010 (includes current '15 squad):
Scoring D: #34
Scoring O: #55
Yds/Gm: #45
RedZone Scoring: #76
Redzone TD%: #74
When I look at these, I see a Top 50 offense. Good between the 20s, good at scoring in general, but bad in the Red Zone. Even a few more conversions per season drives the total offense up enough to warrant a few more wins. I say that because...
The defense under BK has been, on avg, #34. He's had three seasons in the 20s, one season ranked #2, last season ranked #84 (injuries), current season is #41. Basically his defenses have done a "good enough" job to warrant wins, but the inefficiencies in the Red Zone result in mediocre results in the W/L column.
It's not the only reason for the losses. I get that. But it's a big problem and a valid reason why his teams don't get to the 10-win threshold. You can't consistently be below average in scoring% and sometimes way below average in TD% in the Red Zone and expect to be an elite team. A lot of this is the reason for 1) Closer margins of victory that should have been blow outs. 2) Closer margins of defeat that should've been a win. Two things that I gripe about constantly (because curing the Red Zone woes will practically eliminate both of these).
As a whole, BK's teams produce essentially average results on the field which is why he's had pretty average results in the W/L column. Imo, fix the Red Zone deficiencies and the W/L record will work itself out.
With all that said, BK and Sanford have found a great recipe for success on offense this year and even though the Red Zone problems are still there, the big play threats in Fuller and Prosise have kept them in the Top 20 both in yards/game and scoring.
Edit: The guy also needs to catch a few breaks in regards to injuries and suspensions, etc. The one year he did, ND played for a championship. I don't think that's a coincidence. I think he's a really good coach. Good enough to keep ND in the discussion each year.