The Booker T/Dave Batista fight started because of Batista's mouth.
During the Summerslam 2006 commercial shoot, Batista consistently mouthed off
about the Smackdown brand. He badmouthed the other workers, saying that the
show could not draw without him around to pull in ratings, and that everyone
was hoping he would heal from his injuries quick enough to come back and
"save the show". He consistently degraded the quality of the Smackdown
shows, saying that they "just haven't been the same" since he left, and kept
pointing out that Raw was clearly the superior show.

While these comments were what led directly to the fight, the tensions
between Batista and the rest of the roster had been building for some time.
Since the departure of Brock Lesnar, Batista has believed himself to be
"above" the rest of the roster, and has claimed on several occasions to be
on the same level as The Rock, Steve Austin and Triple H. While his ego
never seemed to be a problem backstage before his injury, he's always been
prideful of his friendship with Triple H, even going so far as to point out
to other workers that he's friends with "management".

The fight clearly did not favor Big Dave, however, as Booker was definitely
taking the upper hand before Sharmell pulled him off of Batista. Batista has
claimed that he was protecting his injured arm, thus giving a reason for
losing the fight.

All parties agreed not to talk about the fight, mainly because Batista did
get dominated and WWE brass doesn't want the public to know that one of the
brand's main drawing cards was decisively beaten in a real fight by someone
who's not supposed to be in his league.