In my experience, Infernape's most effective set is the physical mix utilizing cc + u-turn + stone edge + overheat. This is great, as it's easy to force switches and then u-turn out to another counter. It keeps momentum on my side, and is certainly capable of late game cleaning and wall breaking, but I never use him to outright sweep.
Blaziken doesn't have the same versatility and unpredictability of Nape, and he can't u-turn out of counters. He is almost completely dependent on a speed boost to do much of anything, and this really hurts him with his fragility and mostly predictable moveset.
And yes, I say these things not out of hate, but out of realism. I really like Blaziken, but since it was announced he got speed boost the masses have thought it makes Infernape irrelevant. It's simply not true.