I don't think the kill score or the number of towers destroyed are comparable metrics to a traditional sport's scoring system. The heroes picked, the teams' relative levels, and the specific item purchases are more telling.
Have you considered comparing the entire three or five game series of DOTA to a single game of a sport? Think of each game like an Inning or something.
...and then Shaq picks up the guy by the neck and punches him in the face for 20 minutes. It's just sad to watch at some point.