And that's where I think he's running into problems. Anyone who's written anything knows that momentum is key. It seems like with Parker, he (Stoper) has momentum and the story is flowing well. But I think you're right, it's time to put Parker on the back burner and advance other characters. If that's what Stoper is doing, I could see it killing momentum. Maybe he's really enjoying the Parker story, and it's coming easily for him. It could be hard to switch gears to new characters that are basically starting over from zero. Now Stoper has to take himself away from a story that is gaining momentum, switch to a story with no momentum, and find a way to make that story just as compelling. That's a tall order.
I think this is a problem we see in a lot of high quality games. They introduce a lot of characters but then have a hard time developing all of them. On paper, when the story was conceived, it probably seemed like a good idea, but once you get into the game, it's hard to balance all the characters. Some will work better than others, and when it isn't working it can be a drain because you wish you were spending your time on a character that was working.