Tactful ways to inform people that they're playing badly?

[Vahlnir]

I mean...then why even bring it up?

See, if I was tanking and you said that out of the blue like that, that would piss me off a bit and I'd most likely just ignore you. That's a small nitpick and by even mentioning it you're giving off the vibe that I don't know what I'm doing/you think you're superior to me when you are not.

Nah, I don't think that they were intending to come across that way. Personally, I didn't read it as such, and I'm a tank. lol I only wanted to clarify that sometimes things work a bit differently, which they acknowledged. It's not really a "small nitpick" though, imo. If it helps, it helps! People should never ignore good advice if it improves their performance. Well, as long as it is being given in a respectful manner at least. And if the person currently in question put it the way they did I wouldn't find it offensive. It'd be a genuine question or concern.