I would say that the cup games he's played in have been fantastic for his developing, and many of them have been tougher than some of our league games.
They've been OK to get him where his is now, but a cup game every 2 months when he was 17 was a good step in his development. 2 years later a cup game against lower league opposition every 2 months isn't going to cut it.
Everyone knows this, IMO that's why Pep's gone on the charm offensive in the media, praising and talking him up 3 times already in a 3 week old season. He knows that Phil needs to start playing more regularly.