sascha: i recently posted about this straight-pool phenomenon where one day you can look like a pro and the next, a novice. if it's any consolation, i've see excellent players too hit the 14.1 wall. one of the keys i believe is to be well rested. also, sometimes you are in the beginning stages of getting a cold and don't know it which effects concentration. then there are other times, for unknown reasons, your brain just doesn't work as fast as the previous day yet we try to maintain the same playing rhythm. this leads to a slew of little mistakes that magnify themselves as the rack progresses. sometimes i keep track of my mistakes which keeps me from being surprised by the dismal outcome.