As others said, it's a culmination of problems, and last night's match was pitiful for a variety of reasons. WWE and Del Rio did EVERYTHING they could possibly do to try and rally support for Batista. Del Rio faking the injury, attacking Batista like a shameless coward, dominating 95% of the match.
After all that, the fans still shit on Batista. And it's clear Batista is not in ring shape. He was gassed at the Rumble, and he staggered through last night's match. To make matters worse, the "Boo-Tista!" chants were so loud Jerry Lawler had to acknowledge them during commentary.
Also, think about Rock's return in 2011. WWE went through a thorough build before Rock VS Cena at Wrestlemania 28. Hosting Wrestlemania, the interference in the match with Miz, the Survivor Series tag team match, all the promo duels. Rock didn't show up on his first Raw, and announce the match with Cena for Wrestlemania 27, and we're talking about The Rock here. He's a much bigger star that Batista in the ring and outside the ring, and it's not even close. But WWE took their time to work Rock back into the mix. On the other hand, Batista had one appearance on Raw, and won the Royal Rumble the following weekend?
And you can't pull the smarky crowd excuse every week. With the exception of his tepid positive reaction during his Raw return, Batista's reactions are consistently negative, with 90% of live crowds booing the shit out of him.
With the way the Chamber ended last night, it's not out of the realm of realistic possibilities to see Daniel Bryan work his way into the WWE WHC match for a triple threat. In fact, I think it needs to happen. If it's Orton VS Batista one on one, there's no real reason to keep the title on Orton after building up Batista's return and having him win the Rumble. And the last thing you want to do is close out Wrestlemania with the unsatisfying and negative image of 70,000+ or 80,000+ people booing and heckling a WWE WHC Batista.