Joe:
You've done it again!
It is impossible to say for certain that (pardon my French
) there is an imperfection on Arundel's knob. The position of the bat, the proximity of his hands to the end of the bat, and the focus prevents that. The imperfection is fairly evident, however, on Cahill's (Arundel's Indianapolis teammate) negative. That would seem to corroborate your supposition that the bat was the same one used in several photo shoots.
Kevin
Arundel first; then Cahill