Cena may not have had many feuds outside of the world titles in the past few years, but even when he's not in title matches he still manages to stay relevant. He does a great job of making non-title feuds look great and important, even when they are filler. In 2008 he lost the title feud with Orton but moved on to another angle involving JBL, Cryme Time, and Legacy. He helped make all of them look good during that feud. It was not for any of the championships. That whole summer Cena stayed out of the title scene until he got injured. How about his feud with Miz in summer 2009? Without that angle Miz would never have become relevant enough to even GET to his MITB push. Cena then was involved with the world titles again basically until THE NEXUS.
The feud with Nexus kept Cena out of the title scene for almost a year. It made Nexus' members look great and without Cena this angle would have flopped. It was originally supposed to be Trips rather than Cena, they made the right decision to have it be Cena. The feud made Barrett into what he is today and saved the rest of Nexus from getting future endeavoured other than Tarver. I do realize that Cena is in world title matches and feuds nearly all the time, but he still manages to stay relevant when he's in non-title feuds because not only does he make the fans care about those angles but he does his best to elevate whoever he is feuding with too.
The feud with Nexus kept Cena out of the title scene for almost a year. It made Nexus' members look great and without Cena this angle would have flopped. It was originally supposed to be Trips rather than Cena, they made the right decision to have it be Cena. The feud made Barrett into what he is today and saved the rest of Nexus from getting future endeavoured other than Tarver. I do realize that Cena is in world title matches and feuds nearly all the time, but he still manages to stay relevant when he's in non-title feuds because not only does he make the fans care about those angles but he does his best to elevate whoever he is feuding with too.