people tend to play champions which sacrifice mobility for high burst damage or tankiness. they don't pick high mobiliy champs in this meta anymore because high mobi champs grow late.
even though azir got freaking nerfs, he is decently a strong pick becaue Riot improvised his mechanics, he can do his frogjump easier, no need for CDR items and new mastery tree gives him +1/4 of his starting mana as bonus. at level 3 he can allin with basic W+aa+Q+E+aa+ignite.
no one can gank Azir if Azir sees the enemy jungle's coming at him. if you see him moving towards you, just create a soldier between you and him and cast q and e. (your q wil slow him down if its accurate) if you can do that combo (kinda alistar's) you will be dashing at him but you will change the route and draw a half circle, he wont even touch you and you're gonna let him confused. (banana jump) if you fail at this combo; which all of your skills will be gone, and damage to enemy jungler; even if you die, you'll take of his half hp. if your ult on cd, you can get 2 scores, which is pretty worth for one death.
azir starts with doran and 2 hp potions. buys luden's echo asap. magic penet. boots second, nashor 3rd, rylai, rabadon and zhonya. don't hesitate to buy luden, it'll give you huge poke damage and your E can proc it twice.(movement charges it).