CaAP101, the reason you "seem to lose big" only in big counts is that's when you're going to have your big bets out there. You're not a huge favorite to win the hands at higher true counts, so this is where the majority of your variance is going to come in to effect. Your advantage in the bigger counts comes from getting better hands (so will the dealer), getting more blackjacks (so will the dealer - but you get an extra 50% pay where the dealer does not), the dealer busting SLIGHTLY more often, being able to take insurance while the dealer can't, surrendering while the dealer can't, and your splits and doubles working out better SLIGHTLY more often. You're not some huge favorite at TC +4 to win the hand (win%, not EV). Of course you're going to make the most and lose the most when you have your biggest bets out... Makes sense.