There's no evidence Pep has ditched Rodri for Gundog. He made a change today based I would think on an opposition that he expected to sit deep and giving Rodri, who is coming back from injury, a rest ahead of the trip to Burnley. I'm sure Rodri was penciled in to start at Turf Moor even before Gundo got himself a suspension.
Teams run straight past Rodri when they break anyway. Even look at the build up to the 2nd goal(forgetting the gobshite a left back) the Newcastle player just breezes away from Rodri.