Stevenson lost a unanimous decision to Javier Vazquez, and he gave a lackluster effort in the process. The judges scored it 30-27, 30-27 and 29-28 for Vazquez, and it wasn't so much that Vazquez fought well as that Stevenson didn't fight well. For whatever reason, Stevenson just doesn't have it right now.
After fighting for the lightweight title in 2008 and having an impressive two-fight winning streak as recently as 2009, everything has gone badly for Stevenson lately. Starting with a February 2010 loss to George Sotiropoulos, continuing with losses to Mac Danzig and Danny Castillo and now with the loss to Vazquez, he's dropped four in a row. It's very, very rare for the UFC not to release a fighter on a four-fight losing streak, and there's not much reason for an exception to be made for Stevenson.
Stevenson is 29 years old, which isn't ancient for a fighter -- it's still possible for him to turn things around and get back to fighting at a UFC level. But he clearly needs to shake things up in his training, and prove he can win a fight.
He'll get the opportunity to fight somewhere, but it's highly unlikely that it will be in the UFC.