Recently I have been hearing the phrase "post up" is this something new in the bowlers release and what is it trying to accomplish and how is it done if that is what it is?
Posting a shot is about the balance at the point of release. When you post, you can appear like a statue, perfectly in balance and unmoving.
What may have been offered, is the advice that there is to much pre and post shot movement when you throw a ball. That is a reflection of lack of balance and unnecessary motion causing you to roll the ball inconsistently, usually followed by falling off at the foul line or hoping.
Thanks for the question. Good luck and good bowling.