I'd have thought every player insisted on starting every game as it would get the best out of them.
Everyone would like a long run of games, and often improve as a result.
Unless it's contractual or some agreement (that Fellows didn't get) that he's to be a starter, then he takes his chances.
Perhaps, as the only real option for his position, he's there by default.
As you mentioned earlier, I'd like to see Matsuki in there at some point (off the bench, if Azaz is looking tired).