I've played my first real BSG game last week with three players and the humans got wiped out before we even jumped once...
I did some calculations to figure out if things get easier or harder with more players. What I found out made me wonder how player manage to beat the crisis cards at all.
Average difficulty of a crisis is 9.95 points. Average value of a skill card is 2.14 points. Average chance of a skill check in a crisis card is 58.6%.
Every human player gets 5 cards in his turn. Every cylon player gets 2 cards in his turn (when revealed).
Assuming every card can be put to good use in a skill check we can calculate the amount of points the humans can field and the amount of points the cylons can field in every full round (where every player had his turn). The difference is the amount of points in favor of the humans. That divided by the number of players and 58.6% is the amount of points in favor of the humans per skill check.
Depending on the number of players/cylons the points in favor of the humans are:
2:1 ... 9.75 3:1 ... 11.89 2:2 ... 5.49 3:2 ... 8.05 4:2 ... 9.75 3:3 ... 5.49
Aside from the best case scenario at 3:1 there is no situation where it reaches the average of 9.95 points per skill check. The destiny deck is roughly balanced (average of -0.1 points per check) so we can ignore this.
Conclusion: Aside from somehow drawing more cards the humans cannot win every skill check even if they were to play their cards perfectly.
So how should the humans approach the skill checks on the crisis cards to win as much as possible?
Option 1: Discuss which ones to fail and which ones to beat.
Doesn't work so well since the cylons will also know when they need to fight a check and when they can save their cards. Thus the ratio of cards remains the same.
Option 2: Use XO's exclusively to draw additional cards. One additional card per turn would be enough statistically.
Option 3: Try to undercut every crisis just a little in the hopes that the destiny deck will make at least some of them pass...