I was high on them coming into the season and they've more than lived up to expectations-- really surpassed even my higher-than-most expectations. Two things that could trip you up:

1. In most of the games against Tier A opponents/opponents with notable size, Purdue is getting outrebounded. Outside of a flailing Arizona, every other team with respectable rebounding/size has outrebounded you.

2. Purdue's increasing reliance on jumpshooting. In conference play, their FTA/FGA ratio is 29.3-- which would rank around 300th in the nation over the course of a season.

If a team has an off shooting night, three things are required to counter that: a lack of turnovers, strong offensive rebounding, and a high rate of free throw attempts. That way, even with bad shooting, you can win by sheer volume of point opportunities. Purdue has been pretty good with turnovers so far this season, but the offensive rebounding isn't strong against good opponents, and they are getting to the line at an increasingly low rate. (Their percentage of points that come from 3s also continues to rise.)

So the nightmare scenario for Purdue is easy to see: the 3s don't fall one night in a single-elimination tournament, they're falling well enough for the opponent, and Purdue doesn't have the shot volume to survive the night.

That's a long term "sky is falling" concern, of course. Short term, they've got insane balance on both ends, a strong PG, strong wing, strong set of bigs. They shoot lights out, move the ball beautifully. They have two Big 10 POY candidates (which probably means they'll cancel each other out, but it's a good problem to have). They should win the Big 10, as no team in the conference has their combination of talent, balance, and consistency, and the Big 10 is weak enough this season that a 4-loss season for Purdue is totally within the realm of possibility-- which would give them a real shot at a 1 seed.

I would probably just want to see Purdue have a couple of off shooting nights against good Big 10 opponents to have them realize the solution to that problem isn't "keep taking jumpers." We've seen many an elite shooting team face early elimination because they assumed the shots would keep falling. If the free throw rate or rebounding improved notably, then I'd be a lot more confident putting them in my Final Four.