Watching the Pool match again, I agree that the "pen" may not have been clear cut - although I happen to think it was. Nevertheless it occurs to me that what Pool have really been benefiting from is not straight "wrong" decisions, but those where there is any element of doubt - in other words where the ref has a subjective decision to make. This is far more subtle than straight right or wrong, but it's probably where the refs have the most influence. Sure that penalty we should have had against them was pretty clear cut, but since then there's been quite a number of less clear incidents.
They don't get criticism because the pundits just say stuff like "well you can see why the ref gave it / ref didn't give it". The trouble is that their opinion changes according to which team is getting the decision. So if the decision could go ether way, then half the time (or at least some of it), the decisions would go against Liverpool. The difficulty is that so far this season the decision never seems to go against Liverpool. And I'm left with the feeling that we've earned our 3rd place, but Liverpool have been given 2nd.