re: Did we luck out with BK?

No.

At the time he was hired Kelly was firmly entrenched and having success at ND. In fact, ND had an outside shot of reaching the CFP for the 3rd time in 4 years when Kelly left. There was really no "luck" about it. I think, and he has suggested as much, Kelly wasn't looking to leave ND. However, he knew from past experience that even if he reached the CFP it was unlikely his ND team could compete with a Georgia, Alabama, etc. He just couldn't get quite enough players to compete with those programs due to the recruiting restrictions at ND. At 60 years old Kelly wasn't leaving ND unless it was to go to a place where he could be a legitimate NC contender. Enter LSU.

Over the last 30 years or so, only ONE school in the nation can say they've had three different HCs win national championships. Two of whom are FAR less respected than Kelly. Don't believe that? Then tell me why in a world as competitive as college football are two former NC winning coaches (Miles and Orgeron) unemployed with the best opportunity available to either of them being one of the worst power conference programs in the country in Kansas. The fact that LSU cold win two titles (play for a 3rd) with two HCs the college football marketplace generally perceives as bozos showed Kelly just how strong of a program/job this is. When the LSU job came open Kelly could recognize it was the best opportunity for him to win a NC. And an opportunity, with Kelly at 60 years old, was unlikely to present itself again in his career. So he pounced.

LSU wasn't "lucky". Kelly is here because the LSU program is strong enough to draw the interest of ANY college football coach looking to reach the pinnacle of success.