Ok I take your point. When I say tiny squad I am conflating several issues into one that I don't really have a name for. One is we are unbalanced with so few defenders.
Another is we have players in the squad who Pep refuses to play in normal circumstances, like McAtee, now even if he isn't as good as our other midfielders, I find it hard to believe that surrounded by our normal squad we would lose if he played more against Ipswich, Southampton, Bratislava, Prague etc. Him playing one minute every two weeks doesn't help reduce the burden on the first team of help him develop.
Thirdly we don't use to seems subs that much, when we can change half the outfield each game. We also don't seem to use the academy as much as other clubs. We also go too strong in the league cup, and is still affecting us now, despite Pep saying it was unimportant. Plus more games at club and national level means we need a bigger squad, even if just using the academy more.