Barry Greenstein talks about the big hand on HSP S5-E2 . Barry makes a big mistake in his thought process. I'll try to boil it down without too much of a spoiler.
Basically Barry reasons "I either have the best hand, or if I'm behind I could spike a card to get ahead". Lots of people use this reasoning, and it's wrong.
The basic flawed reasoning goes like this : I think I'm behind, but I'm not sure. Maybe I'm ahead 10% of the time, so I have some value from that. I have a thin draw, maybe I have a 10% chance of improving to beat what I think his hand probably is. So I add those up and I can call up to 20% of the pot, right?
No. Wrong. The big problem is there are more streets of betting. If you are drawing to a thin draw, you really want your opponent to have a big hand that will pay you off if you hit. On the other hand if you are hoping your hand is good, you need him to have a weak hand. Those options conflict and don't add up.