Yeah, let’s start here.
Let’s imagine for a sec that the steal with a few seconds to go was defensive skill, not luck. Arguable for sure, but let’s stick with that.
Let’s focus solely on the shot. A shot from 40 feet out. What percentage of the time does that shot go in? Maybe 25% of the time?
Which means there’s a 75% chance he misses that shot. Had the shot not went in, they of course would have lost the game. Therefore, they were decently lucky to win that game.
The last play surely involved luck, and we'll never know if coaching made any difference in how it played out. But even without the last sequence, they would have beaten the spread by 2.5, so there's some credit/blame to be had regardless.