Small players need 3 things to be considered useful to most teams: pace, stamina and aggression, In the case of Pep, a fourth criteria is required = Intelligence.
A small player can loose one out of 4 and still be useful, for example, Bernie has lost his pace but still has stamina aggression, and Intelligence (when he's not loosing his head).Lahm and Kimmich never had pace but had a lot of intelligence, physicality and stamina and Pep wanted that in his Bayern team. Rico on the other hand has intelligence but lacks most if not all of the other 3, he needs to go on a personal training routine to improve these things, I still like him as he is a very intelligent player but he has to realize that something is off and strive to improve these areas.