You can tell if Pep trusts the players by the games he plays them in.
(Not sure if you actually looked at the data linked for each player?)
Of the first 4 games of Ake's first season, (when no one knew which team was going to win the league), Ake played 3 full 90minutes at CB, scoring 1 goal, (in the other game he came on for Mendy at LB on 71 minutes). Then he got an injured groin followed by a hamstring injury. His season was hampered by injury but was regularly playing whole 90 minute games when he was fit.
With Nunes, he only played 90 minutes of PL football for us, all season, in 3 home games to Luton, Burnley and Forest.
IMO it's quite clear Pep doesn't trust Nunes yet.
I agree if there was nothing at stake Nunes would likely have been given more game time.
Phillips was clearly another player who was not trusted in tough fixtures when something significant was at stake.