All members of what I call "The 15 Minutes of Fame Club".
Just you because recieve a push, win a world title, or headline a pay-per-view, that dosen't mean you become a main-eventer. As backwards as that sounds, that's how WWE operates these days. All of the men named above got a brief taste at the top, and the second their temporary push ended, they fell back into the mid-card.
Like I said, WWE has only created 3 main-eventers in the PG Era - Sheamus, CM Punk, and Alberto Del Rio.