I see what you're saying Corduroy -- a lot of these 16 seeds are filled with upperclassmen who've been with the program for 3-4 years with the same coach who's instilled his philosophy. So for the last 3-4 years your offseason stuff, practices, walk-throughs, game-planning, etc has been about how he wants you to play. To all of a sudden to tell a team that in the biggest games of their lives, with everyone watching, that we will play a way we never have before-- that just seems like a tall task for any player, it also could really hurt their confidence--it shows them that the coach doesn't believe enough in his style that's he's drilled them into them to use it in their biggest game ever.
What makes you think they'd be efficient at it too? If you're a team that wants to go as fast as possible no matter what, it might be due to some deficienices you have in your half court offense. So now you're playing UNC or UVA or Kansas and you decide to slow the pace and get into your half court offense? I feel like it'd end up being a bigger blowout. Yes, posssessions are limited, but to me losing 69-38 playing a completely different style than your own is worse than losing 105-79 using your style. You stick with what got you there. UVA tried to slow the pace vs. UNC in the ACCT title game and look how that turned out for them.
Not all 16 seeds play like Princeton, but the ones that do will have the best chance. I agree, most 16 seeds that like the uptempo pace will not have a shot vs. 1 seeds, because you're trying to beat them at your own game; literally their only shot is get ridiculously hot from deep. A team that plays similar to Princeton all year and is used to that type of game could have a shot, but this isn't a "fake it till you make it" thing for an uptempo team trying to keep the game in the 50s