I think the Eagles were frustrated with him. Put aside the fact that he has some known off the field associates that are linked to gangs. He got kicked out of practice according to their media a few times, he openly fought with the WR coach (including one massive blow up on TV against Minnesota), constantly was late for meetings, rubbed some teammates the wrong way, admitted that a few years ago before he got his new deal, he basically took that season off because he wasn't getting paid like he wanted............... then add in the fact he kind of hinted he wanted a new deal at the end of the 2013 season and I think they were just tired of dealing with him.
What I found somewhat funny was that after he got cut, the support from teammates on Philly seemed blah. No one seemed to come out and say what a huge mistake they made.