Unless I have short term memory or something, it has been a while since the champ end Raw with the last segment or match.
Pretty much this but I do think Kane and Cena closed out the show quite a bit too.It's quite easily understood. Punk was closing out Raws back in December, January and the first three weeks of February. Cena was actually taking something of a back seat with the whole ensuing Kane angle. But the last Raw Punk finished out was February 20 in Minneapolis. What did it take to knock Punk out of that slot? The Rock returning.
Punk would probably have resumed closing out Raws in April following Wrestlemania, only thing is, a guy named Brock Lesnar showed up and now Cena/Lesnar is the (a) angle by a wide margin just as Cena/Rock was the (a) angle by a wide margin the moment Rock returned on February 27th.
He's been cast in the shadow of returning superstars in Rock and Brock and their respective programs with Cena.