Players also can think out their strats better than NPC's that tend to follow at least some kind of pattern. I get plenty of games when I rematch NPC's for cards where they'll do the exact same thing if I play the exact same way. Though sometimes they do mix it up, they seem to follow a pattern.

Players though are different. Since they aren't coded for patterns. That might be why it's getting ahead of you. You might just be too use to how NPC's play.