Wrestling isn't a competitive sport as much as it's a cooperative dance. For a match to work, wrestlers have to be in sync, working with one another to create a back-and-forth spectacle that grips the audience.
The key to wrestling, at least in the old days, was to convince fans that the fights were real and that the moves the participants were doing to each other hurt. In reality, the animosity was manufactured and the moves were less devastating than they appeared. Punches and strikes are based off of slight of hand as much as precision, and wrestlers learn the safest way to fall in order to minimize pain and injury.
As the years went on, though, something changed. It seemed like as more fans learned that wrestling wasn't on the level, wrestlers felt more compelled to make it "real." While many old-school wrestlers still continue to pride themselves on their ability to work "light" and make it look good, strong-style wrestling emerged as an avenue for ultra-physical (and frankly, less safe) forms of combat. Really, it's all about personal preference.
This is a list of the 10 stiffest wrestling matches of all time. While I've intentionally omitted matches that turned into actual fights, in many of these bouts, the participants might as well have been out for blood - the end result wouldn't have been much different.