An example could be, “ Because I think Mutai is a better marathoner on a hilly course.” OR, “I think Mutai was doped out of his mind and had some intangibles going on.” OR, “ I don’t think Kipchoge has the ability to change gears at the end like Mutai did.”
Just give a reason and commit. Then i'll stop arguing with you. Otherwise, you got nothing but your gut feeling/emotions which doesn't cut it on a running discussion forum.