"Yes, if the bowler didn't try everything in his arsenal and abilities to roll his best."
What do you use to define that arsenal? If one pulls a ball out of the closet to see how it works, does his/her best, and still scores much lower than his/her average...would that be sandbagging? What if the bowler has been using certain equipment and torching the lanes, then chooses to bring different equipment which just doesn't work as well? Is a bowler required to bring only equipment that he/she will be able to score with?
That is the biggest problem with bowling. I could bring one ball and average 230+ with it, then I could bring a different ball and be lucky to average 190+ with it, based solely on the ball characteristics. Realistically one could get rid of all of their equipment, get one ball drilled to work "not so well," try his/her best with the equipment they have, and legitimately average low. Said player could later get all new equipment and "become" a better bowler.
The fact that a ball and its characteristics could make one look to have lesser ability than they do...HUGE problem.