does blitz's knockup make him OP? no.
obviously chars like xin and alistar r going to be OP because they r easy to play. Xin: q, right click, w, e, q, right click etc.
alistar: flash, q, w into team
blitz isnt OP because is only initiator is his grab, which is a skill shot. to quote Doublelift, "I remember when I asked Elementz why Blitzcrank was Tier 4, and he replied "because there's only one person who can play him Tier 1." ..... When I play Blitz, I'm constantly putting myself in a good position to hook.. Sometimes I'll pull tanks or tanky DPS off of teammates, and sometimes I'll pull carries into my team to get a free kill. Blitzcrank has an ability that will essentially kill someone, a permanent ghost, a 1.5 second CC on a 5 second CD, and an AoE silence/nuke. So why isn't he more popular than, for example, Alistar? It's because nearly anybody can play Alistar, and it takes a certain degree of finesse and mechanical skill to play Blitz. There's a bigger risk in taking Blitz. What if I miss a hook? It's certainly more likely than missing a Headbutt+Pulv combo. The problem with this mindset is that at a certain point, the probability of missing a reasonable hook becomes less than or equal to the probability of messing up a W->Q combo. Niche champions are hard to play, but the difficulty ends up paying off if you can utilize their abilities to the fullest."
article link:
http://www.solomid.net/blog.php?v=8368