While one could certainly argue that Drummond got "snubbed," it'd be hard to say he was the biggest omission. Point guard Kyle Lowry probably deserved a nod more than teammate DeRozan, and Lance Stephenson certainly warranted strong consideration considering his contribution on what might be the East's best team.
The biggest name in the West that was left out was definitely Anthony Davis, who is playing out of his mind and is coincidentally on the New Orleans Pelicans with the All-Star game set to be played in the Big Easy. Also, no Tim Duncan? You make it look too easy, big fella.
You could argue that the other snubs in the West included big man DeMarcus Cousins, who seems like he is finally starting to have his production match his talent, David Lee of the Warriors or DeAndre Jordon of the Clippers.