Ezreal is still a great adc
Crit based ADC are just so broken right now it's ridiculous. Since the crit changes, Vayne, Caitlyn, Tristana, Draven, Jinx, and Jhin have just been in a state where their mid games are too strong for champs that are supposed to be late game due to the affordability of IE and buffs to RFC and shiv.
Kalista is the obvious exception in that her rend is not crit based but she is still viable because of how good engage tanks are right now. Ezreal never stopped being top tier other ADC just reached insane levels of broken with all the buffs to crit, and they took Ezreal's spot as the best mid game ADC.
while the other adcs get to their power spikes sooner and the game is typically out of reach for him to be effective is why he is bad
so you have mana regen, ad, cdr, and crit and then build into triforce
then finish