I have only a little football knowledge and almost no BB knowledge. But, aided by recent events and certainly to change when Bill wins #6, I am saying right now that Stevens is a better coach in his respective sport then BB is in his.
BB while awesome has basically always had the equivalent to Lebron James on his team. IE the Best player on the field. While I get that LBJ can impact both ends and probably has more impact on a game in its entirety then Brady (though its a interesting debate), the advantage that BB has had having Brady in house is incredible. (...)
I don't want to distract from lovegtm's excellent post or that line of conversation, but baka, this is absolute nonsense. As anyone who's closely watched most of the BB era can tell you, Belichick has play designs routinely, several times a game in all 3 phases, which out-coach and exploit the other team. He makes the most of his resources in roster construction, in matchups, in play design, in player role- and expectation-setting, and in the snap in-game judgments in play calling, timeouts, substitutions, etc. He has lots of help, and he's not infallible, but a close observer has seen opposing coach after coach routinely flub their lines or fail to account for something that Belichick has seen in his sleep - basically, the error rate for Belichick is much, much lower than other coaches, and it has spoiled us rotten. And there was nothing in the 2017 Patriots' season to make us think that he's lost his fastball: he was, ya know, in the super bowl, late in the 4th quarter needing to drive the field once with Tom Brady to tie the game.
And that's in a sport where preparation is everything and coaching can make an incredible degree of difference, far more than in (say) baseball or hockey. The whole game, so to speak, is about play design, reading opponents' tendencies, and exploiting matchups. What we're praising Stevens for here, in a few ATO plays per game, is essentially the entirety of the job for BB and his staff, and he's doing it 80 times per game on each side of the ball. And doing it in a sport where you have 53 players and 11 of them are on the field at once, so it's geometrically more complex than in basketball.
Stevens is more analogous to Jaylen Brown. We've seen flashes of brilliance, we've seen tons of improvement, we've seen oodles of potential... but he hasn't yet had the fullness of success or the consistency of long-term performance to put him in the same category as HOF-level coaches, nevermind GOAT-level coaches in his or other sports. He has everything you'd want to see in a basketball coach, including charisma and the ability to get his players to believe in him and buy in, but let's not go over-the-top here with the recency bias.