Size usually matters, I hate it but let's look at some examples where size really did mattered:
1. First based off Lennox Louis's destruction of everybody he ever faced (let aside for now his to knockout losses with HE REVENGED in a devastation-style), he only struggled against Klitshko. He really laid a whooping down to Ray Mercer and Mike Tyson, even though they are so powerful, Lennox size dominated.
2. Now Klitschko as the examples, he dominated everyone and his size was the big factor, but moment he faced the guy the same size as in AJ, and also in Fury, he choked in both battles. Because this size was bigger than his size.
3. Ruddock Bowe destroyed everyone he faced and was undefeated because he was always the biggest fighter. That is why he tried to avoid Lenox Louis. Finally when Bo faced a fighter his own size, Andrew Gollota, he got a butt whooping 2 *.
4. See how Foreman knocked out Frazier two times. Frasier can never win that fight. Why? Because size matters.
5. Least but not least, Valuev could not be beat, due to SIZE.