I wouldn't use the word "unrealistic", because of course it's realistic. But I'd like to think a cruiserweight main eventer could beat a giant jobber any day of the week, or at least put up a good fight. Obviously not in real life. But if I wanted to see real life fighting, I'd watch UFC. In WWE, it really gets on my nerves when the RAW GM or Teddy Long announce that someone's opponent is going to be Mark Henry, as if Henry has a chance at winning. (Not counting his recent push.) Look at Rey Mysterio, for example. He's pretty small by wrestling standards. But with his position on the card, he shouldn't be "squashed" by anyone. He loses all the time, but he still looks credible doing it.
Looking back, it feels silly. But there's one example that stands out to me. Remember about 6 months or so when Tyson Kidd brought in his new bodyguard? (I've honestly forgotten his name.) He came right out the gate looking like a monster. Then he went against Mark Henry, who at the time was being booked as a mid-card jobber. So I'm thinking Kidd's bodyguard is going to squash Mark Henry to put him and Tyson Kidd over. But it was the other way around. Losing to Mark Henry completely derailed this guy's push and I think we only saw him one time after that. Granted, they obviously didn't think he was ready if they sent him back to development. But my point is, jobbing to a guy like Mark Henry makes you look weak. Anytime an "enhancement talent" beats someone, whether large or not, it makes the other guy look weak in my opinion.
Does anyone remember when Bob Backlund beat Bret Hart for the title after Owen Hart threw in the towel? Bob Backlund lost the title a few days later in an 8 second squash to Kevin Nash. And he was out of the main event just like that.