I seriously doubt that. From his perspective, he's earning more money than he would have here. He's won a Cup already, reached the semis of the CL and has the opportunity to now work with Guardiola.
Why would he be suddenly regretting the move?
Also, looking at the PL stats alone is a bit misleading. His overall stats are 12 goals and 8 assists in 49 appearances. That isn't too shabby, and better than most of our AMs.
So I wouldn't be so quick to write him off. He's a major talent.