What a match up this would be. Marciano has a sorta Jean Marc Mormeck type of style that would make an exciting action fight vs Haye.
Rocky Marciano is an all-time great puncher within his weight range, so I can't say I trust Haye's beard in this one. I think Haye maybe develops a lead in this one with his athleticism, but he's too wild with his offense and would eventually leave himself open for a Marciano bomb. Conclusion: Marciano by KO.
Styles make fights! Just because the Rock was a great fighter (note I said fighter and not boxer) does not mean he wins this easily. The Hayemaker can bang as well, plus he has other attributes. Forget about whose won what, forget about ATG records and resumes. Base your conclusions on style from what you have seen from both, and what in the end is likely to cancel out the other's strengths and weaknesses. I think at this stage in Haye's career though, the vulnerabilities and lack of polish in his finishing I think he falls short of getting the job done. Maybe Rock gets a late tko/ko having weathered some early Haye bombs, and catching David down the stretch as he begins to tire and having expended his energy, trying to get Rocky out of there. But I see a close and exciting fight for atleast 9 or so rounds.