I see Diana in almost every game

she still has burst on one target when even or ahead of their target. so skilled diana players will use her to make picks.

TBH i love her, her laning phase is just too hard for me. i often get zoned when im on her. i reserve her for those zed players because i know zed wont be able to kill me when i rush a zhonyas.

Diana is coming back into popularity for several reasons, the primary is that most of the lane opponents that she would struggle against are receiving nerfs which leaves her in a better spot. She's coming back as one of the remaining strong assassins in the game after others receive nerfs and fall out of favor.

She's also free this week.

People starting to play her because WE played her at IEM

I wouldn't say she is overpowered, She just fits the meta super well right now. She is a good counter to Zed, roaming mid laners seem to be the best thing right now and Diana's roaming is awesome at 6, And alot of the champions she strugles against were nerfed recently.