JPA's form has been poor this season, no question. But then, so has the form of many in the squad - Mellberg, Samuel, Delaney, Hitz, Cole (not to mention Barry early in the season, or Hendrie's hot and cold run).
He's clearly down on confidence - I hope the summer break will help restore him to his best.
And as for being offside because of his knee - garbage. How many times was he offside last year? And the year before that? He often strays in the hope of getting an extra yard. Doesn't seem to work too often though, does it?