The story is always the same.... or very close. We practice & practice, buy new stuff, read new books & we have Better days, Good days & Good ole days where you play well & don't get the rolls.... Many a player has suffered the same situations. Many have given up, only to try again.. Many have settled in & just accept what comes.
Pool is a game where Consistency is Omnipotent. Do you practice banking, playing leave, cue ball position, using the rails & caroms? Do you practice the first shot in every game, The Break Shot..? Do you know how to do these things well... I'd bet not. How many has an Instructor, How many have used Video Analysis, to find their weak points. Learning to do better is a definite possibility, but you have to WANT TO..
Not all of our Champions are NATURALs, some actually learned to be a Champion. Some had good Instructors & some practiced well & learned through repetition. Some do better, under pressure. Our practice has to become Perfect Practice in order to rise in skill level... That's an AXIOM.
If you want to play better, then you will need to do something different, than what you've done so far... Good Luck to all...