Norris was nearly two seconds a lap quicker than Leclerc. The difference was McLaren stopped twice, Ferrari stopped once, and at Monza that's all that mattered.
Lando Norris had pole position, the faster car, and a 1.8-second-per-lap pace advantage over Charles Leclerc. He finished third. Ferrari won with a one-stop strategy that should have left them vulnerable but never did, because McLaren handed them track position and then couldn't get it back.