Instead of comparing with Bahtinov mask, I would just repeat the autofocus routine a few times and see what the numbers are. If the curve looks nice but it isn't repeatable, there is probably something mechanically loose. It looks like you have a step size of 400 and the focus position would need to be repeatable to about 100 or less. If it isn't, then even if the curve looks good - when the focus winds back to the calculated focus position it won't be exactly where it should be.
Do you have backlash compensation set? You should probably set it to a good value and make sure it is invoked when moving from a low number position to a high one. It should overshoot when going that direction and come back.
Frank