Recently they've been resting on their laurels with the "big summer storyline" to sell the PPV and not caring about the undercard at all (what a shock). Last year, you had Triple H sticking his big nose in Cena vs Punk, Orton vs Christian #410, Sheamus vs Mark Henry with little build, Barrett vs Bryan with no build, one of the most hyped Divas' matches in a long time (but was still a Divas' match), a random, unannounced tag match, a Cee Lo Green concert, and a little over an hour and a half of wrestling.
2010's had to have been the worst of all time, there was the Team Nexus vs Team WWE, the Straight Edge Society getting buried by Big Show, Melina vs Alicia Fox (lol), Orton and Sheamus fighting to a DQ, Nexus ruining Dolph vs Kofi, and Kane vs Mysterio. Terrible. 2009's was okay due to Hardy vs Punk and Rey vs Ziggler (Cena vs Orton can gtfo), but if you're a DX mark you'd probably like that one better than I did.
So history says that PPV is going to suck, but how relevant is that this year? We'll see what happens.