And in typical City mid90s style, because some have decided that he "isn't good enough", they get on his back from the moment he appears on the pitch, rather than supporting and making him more confident.
Funny you mention Cancelo. It was (imho) him thinking he was a creative playmaker which drove Pep mad and made him push Cancelo out and bring Lewis in.
Cancelo played some great passes, but also lost possession and we know what Pep thinks of that. Lewis came in and just gave the ball to the more talented players - like Phil and Kev and Bernardo etc. Pep wanted them to be the creative players, not his inverting fullback.
Problem now is that everyone wants a bit more from Lewis (including defensive ability etc), but his whole game is based around simple and having quality players to give the ball to. The less of them in the team, the more he struggles.