Fallon's Tonight Show, Stephen Colbert's Late Show and Jimmy Kimmel Live! have all seen their viewership drop this season, but Fallon's ratings have fallen the steepest -- 17% vs. 5% for Kimmel. That's why Fallon is now slightly behind Kimmel in third place in total viewers (Fallon is still No. 2 in the demo). NBC tried to follow the Colbert model of bringing in a morning news executive, Jim Bell, to oversee the show. But that didn't work. Now Gavin Purcell, who helped launch Fallon's Tonight Show, is returning on an interim basis. Could he bring back the old Fallon? "As his producers got conscious of what other shows were doing, they tried to reshape him," says Bill Carter, the former New York Times TV writer who wrote The Late Shift. "The bottom line is, let Jimmy be Jimmy."