I like to think that there’s two reasons.

1. Jamie had come through the ranks at Pep’s Man City, and as beard points out in his presentation, Pep had adopted his own brand of total football at which means Jamie would have a good understanding of the system and how to be in different positions already.
2. (I think this one could be more important). Jamie spent the second season becoming a team player and less of an absolute prick (paraphrasing Roy) and lost some of his prickish brilliance, which they tried to fix with their signal. They want Jamie to be Jamie, the real Jamie, the Prick. They don’t need him to pretend to be anyone else to get the message of what they’re trying to do.

I might be wrong and people will have their own opinions but these are mine.