Some thoughts from Germany here.
Yep, Gundogan is a bit of a summer time player who shines when the team is up by 3.
You won't see much from him when you have to fight to turn a match around.
Gundogan is not a holding DM. He is not physical enough, that's not his game. He has got a brilliant technique, if you give him time and space.
He is most dangerous when he has enough space in front to deliver the ball to the forward line.
He did quite well at Dortmund. But in Germany even lower ranked sides don't park busses. In the EPL Gundogan is missing the amounts of space he has had in the Bundesliga. That's why we don't see so much from him.
I also agree that his type of game is similar to Silva and KDB (Yaya as well): creative OM. I always thought he came to City to share the workload with Silva who always is missing some matches over the season due injury.
Gundogan is a victim of Pep's system, too. If City would play more compact and a bit deeper to pull out deep sitting teams, I am very sure Gundogan as well as KDB would be able to find the likes of Sterling, Sane or Sergio by quick vertical passes into the free space, not directly to the player.
Pep's possession game is highly predictable and easy to defend. Where is Pep's tactical brilliance? What about his cleverness??
If we don't develop strategies to open those free spaces our creative department will never be able to play to their strengths.
I don't understand how Pep cannot see this predictability. He is sticking to his philosophy not caring if his team is able to do so or not.
Pep's pride cost City a bit too much atm.