I may be an idiot for taking your post seriously, but I enjoy the subject, so I will respond.
Two years ago, Painter had what I think was his most talented team, yet by all metrics they were not good on defense. It was frustrating to watch them play disconnected basketball, with one player not knowing what to expect from another.
This year, Purdue does not have a team that should be great defensively. This is a team built to score and they are great at what they do. Yet, Purdue had a top 20 defense. It really is an impressive feat when you consider that this is the era of positionless basketball and Painter is playing a very traditional line-up. The key is that they are playing intelligent basketball as a unit, following a well designed game plan.
Painter takes D so seriously that he has two assistant coaches focused on it. He also hired an outside analytics firm after last season to help him optimize points per possession on both ends of the court. Purdue comes into every game with a plan to take away what the opposing team does best. For Gonzaga, it is not hard to see that they were running an extremely effective pick and roll offense, hurting teams from three and at the rim for the second half of the season. Purdue never let them get comfortable from 3 and really took their inside game away after a slow start. Sure, Gonzaga was able to get some open pull-ups and some favorable switches, but generally they were forced into a lot of difficult shots over Edey where Purdue was able to stay sound and not foul. When combined with great offense, that is exactly what Purdue needed to do to win comfortably.