The interesting part is that his move ran counter to what many would have expected. Losing the rebounding battle and he goes smaller. In hindsight it makes sense because basically, it we're going to lose the board anyway then let's try to outscore them. But I am betting none of our armchair coaches would have thought to make this particular move.
It's worked largely I think due to a somewhat unrelated factor - attacking Lopez more aggressively in pick and roll plays, which he has struggled to defend. It has been limiting his ability to stay on the floor. In games 1 and 2, Lopez played 34 and 32 minutes respectively. In games 3 and 4, he played only 21 and 22 minutes.
This was one of Stevens' best adjustment in the series, along with starting Green in place of AJ, and I take my hat off to him. And as mentioned above, using Smart as a ball handler instead of off-ball, where the Bulls have basically completely ignored him, has been another huge adjustment.
My faith in Stevens has been restored after some serious doubts crept into my mind after games 1 and 2. But we have to win this series for that to be maintained.