Does anyone know if provoke generates a tiny bit of enmity like any other off-GCD ability? It seems like kind of an awful use of the ability, but I had a tank use that as a defense when I pointed out that he was wasting provoke by using it immediately AFTER shield lob when he was doing trash pulls. What was worse was that he'd occasionally lose the hate to the ranged DPS or healer and had to kite/shield lob to get them back in range and under control.

To answer the OP: My view is that as long as you aren't a dick about it, it doesn't really matter how you say it. If the person takes suggestions/criticism/whatever well, they will welcome any advice on how to improve their play and either ask you to clarify or make a mental note to go and read up about it afterwards. If they don't, the best you can do is just shrug and hope the tank doesn't cause too many issues for the rest of the instance, and hope you never get stuck with them again.