Yeah, tightening up is your mistake. And it's not really your fault, it's a general misconception that has even made it's way into books and guides, etc. When people are playing a very wide
range, you need to loosen up. If you are playing 80% of hands, then I can profitably play 60% or more of hands when I have
position. Assume we are better postflop, and we will
rack up against the
fish playing 80% of hands. We just need to find out his tendencies and tailor our ranges to
exploit that.
For instance, if he is playing 80% of hands, so we decide to play say 50% of hands (other factors such as players left to
act,
position, etc needs to be taken into account), and we figure out that he just bets 3 streets with a very high frequency. In that
case, that means his betting
range has loads of bluffs/
air/weak hands in it. Which means, with our wide
range, we should start calling with a wider
range of hands.
Say he calls with a wide
range, then we need to shrink the
range of hands we
bluff with (because he doesn't
fold), and we need to widen the
range of hands we
value bet with (because he calls with worse so often). So in this
case we can
value bet his with a lot of hands, hands that would normally be considered '
marginal'.