Again, what makes you sure you know better? What helps you identify Gundogan's weaknesses better than the manager who sees him in games and training for several years now?
Because the results are unsatisfactory, there must be a simple explanation, the simple explanation must be related to a single player and there is no better candidate for that player in midfield and attack than Gundogan, right? Have you entertained the possibility that things might be much more complex than that and that Pep factors in circumstances you have no idea about? Maybe he knows what's wrong with our performances this season. And that the reasons for them are not down simply to 1-2 players and go deeper: the fact hat we have injuries, aging legends, have won 7 from the last 8 trophies on offer in England and the motivation is not quite the same or a bit of mental tiredness is kreeping in, or we were also a bit unlucky to concede 5 goals from 7 shots on target against Spurs and Norwich, etc. etc.?
Don't let a bit of thinking get in the way of simplistic explanations though. It's so much easier to blame Gundogan and Pep's inability to see how incredibly limited he is for our bad results.