Just like the hoops transfer portal it's money first and then playing time next. Pena was going to be on the field plenty and be paid well (not as much as the big dawg offers but enough).
However if Hixon's new offense is only going to target him half or a third as much then that's a problem for him when Sundays come. Also remember Fran was asking Pena to become an elite punt / kick returner which may have been a way to keep him involved as much as possible to help Special Teams but likely would've taken offensive reps which may have been a problem for Pena. *Good way to get Injured is taking every return rep with a special teams unit that has not been great...
People want to pretend it's schedule or deficiencies from people leaving last year. It's none of that crap. We're building the offense overall around what Rickie can do, not pretending like we have a replacement McCord or that Pena will put up the #'s he did last year.