ADC season 2 vs season 7:
Season 2: Were balanced around doing dps to objectives like towers and baron. Late game they could take down a tank if they focus them for 7+ seconds. However, they could be assassinated very easily if they misposition. They had a very horrible early game and required a support to get them through and peel for them in teamfights with cc.
Season 7: Are now balanced around them being "tank destroyers". As such they are the only class that has "sustained burst damage" which is a completely retarded concept. Right now they can destroy turrets in less than 3 seconds late game and are capable of bursting squishies faster than even assassins can. They now have early games on par or even better than other classes. Their midgame is comparable with mages, and have an insane late game.