I would class a fifth place finish in their first season in the PL, and having a squad that boasts the likes of Krul, Coloccini, Cabaye, Tiote, Cisse, & Ben Arfa as pretty successful.
That's the problem with 'success' nowadays. A fifth place finish with no silverware is considered to be a successful season...
And FYI it was our second season back in the PL.