Exactly. That wasn't a fistfight. McCluskey, a big guy, aimed and applied for maximum impact while Michael was being held still. Michael was probably treated in an emergency ward and told to make an appointment for corrective surgery to realign his jaw, make sure all bone fragments were removed properly, and to treat damaged facial tissue. Of course he never got that chance, and he probably was wary of getting it done in Sicily, either because he feared he might be assassinated in a hospital, or more likely because he didn't trust the docs. NB: In Sicily, Dr. Taza, a fellow guest of Don Tomassino's, offers to treat Michael, but he declines. Michael knows that Dr. Taza, like so many other Sicilian doctors, got his medical license via the Don's influence, not through his brilliant talent.