Cynicism!

[Tirion]

Is it possible that Rambis is a competent coach who knows exactly what he's doing...that he's been doing what his employers wanted him to do...and that what his employers wanted him to do is tank?

No, he's just clueless.
Coaches very very rarely tank on purpose, it looks bad on their resume.

[CoffeeJanitor]

While the team is young, it's not exactly the void of players with playoff experience that should know how to close out games. Beasley, Darko, and Luke have all been there and understand those pressures.

Beas seems to have focus issues and has never been that guy
Darko has been a career victory cigar/off the bench guy (although I'm lovin his play this year)
Luke is a backup PG. He shouldn't be expected to close out games.