Ekko not living up to expectations

"We’re about to send League’s next champion out to PBE! Ekko’s a powerful skirmishing assassin who thrives in extended fights, using his mobility and crowd control to slow and stun enemies as he whittles down his targets. And if he starts to lose a fight, the brilliant boy from Zaun can rewind time a little and try again."

That's the description of Ekko we were given before release, but I want to focus on one main point "Ekko’s a powerful skirmishing assassin who thrives in** extended** fights, using his mobility and crowd control to slow and stun enemies as he whittles down his targets" Extended fights, whittles down targets, but then he's released with an ap scaling on his abilities that gives him Leblanc level burst, I may be wrong but for a mage who's supposed to mainly focus and rely on utility doesn't his damage output seem a bit high?