Buehrle is basically the model.
You want that arm cocked (upright), hand and forearm pointed toward the corner base at foot plant, and you don't want a stiff front leg.
But really the problem isn't the arm action itself. A pitcher can have an ugly Inverted W and still get to where Buehrle is at the critical moment. The messy arm actions just lead to an increased likelihood that a guy's timing will be off when it matters. They are like proxy measures, because most of the time there is no high speed camera of a guy's motion.
But there's a reason that people do the "tricks". They increase stress on the arm/elbow/shoulder, and that stress can = more velocity!
Guys (coaches) can trade a bit of health for a bit of velocity, in theory, sort of.
Also this isn't science and you're talking about increases in % chance of getting hurt - pitching at all, even with perfect form, is unnatural and dangerous.