The winners are pre-determined, the blood however is most times a blade job, where a wrestler will just cut himself and he will bleed but there are times that a wrestler bleeds the hard way (meaning it's a real cut)
NBC ran a "Pro wrestling secrets revealed!" show a couple of decades ago, an "unknown" wrestler was speaking out (It was Harley Race.) admittedly everyone knew how it was with wrestling, but NBC went all the way making it all about being fake...
I don't see the big deal about it being fake, you have the storylines (fake) in ring action (half fake, half real.) and stuff....there are still real injuries though.