It's an old cliche, but serves fairly well here - "It's not the dog in the fight that counts, but the fight in the dog" This same theory applies to individual arts as well. It all boils down to the practitioner or fighter involved having proper conditioning and/or a "no quit" attitude. Oftentimes this can't be taught or bought, but is rather inborn as HEART. No doubt, if a fighter is well rounded in stand-up and grappling skills he'll have more cards to play in any given game.
We confide in our strength without boasting of it, We respect that of others without fearing it!
Thomas Jefferson 1793