How do you tell someone that they are not as good as they think they are?
I don't wanna give you a huge story here so I'll try to keep this brief. Someone who is very close and dear to me, plays WoW too. While I lead the progression team of my guild (around world 35-ish on 10 man at the moment, and no this isn't for me to brag this is to explain my point) she raids in our guild's second team and they are still struggling to clear normal Throne of Thunder.
She claimed that she is good enough to be in a top 50 team worldwide. Now I'm not going to get into details of why she is not, but all I will say is that she started playing WoW in Cataclysm, and her only raiding experience in "heroic" content is Dragon Soul after like 20% nerf and about 6-7 heroics in T14. She is still a fairly new player and while constantly improving, she is just not a world class player yet. She just falls into the trap many newcomers to "serious" raiding fall, that after they make a big leap forward in their game, they think that's all there is to it.
The problem occured when I tried to tell her -mind you, as politely as I could- that, while she is improving, she still has a long way to go to reach the level of my raiding team. I also told her that, for example, while I am obviously a good player, I still am far away from being as good as Paragon are and that there's nothing wrong with not being the absolute best yet, to avoid sounding arrogant.
But the result of this was that she got hurt and -stubborn as she is- refused to listen to me and just called me elitist.
So, how do you tell someone you care about that they are not as good as they think they are without sounding arrogant or hurting their feelings?