I think he is similar to Jeremy Doku, but same for me that I didn't watch every single game, but every time I saw Doku play for like 30 minutes because he was coming from the bench, I was wondering why Pep didn't give him more chances to be a starter. Maybe he wasn't as reliable as I thought he is, but you can't just go with goals scored. Doku, for instance, gave the defending team such a hard time that all his teammates in the front had so much more space for themselves. That's another important effect of players like Doku or Frimpong.
Because he lacks end product. He's like that story about a cow that gives 100 liters of milk and then accidentally spills it every time.
I like him, but it's City. You have to be best of the best, week in week out. He has the potential to eventually get to that level.
Generally, reliability depends on positions. There are many reliable defenders and midfielders, but not many reliable wingers. Their game heavily depends on end product, which is incredibly hard to maintain consistently.