Obviously these kinds of knobs were common among older players, but does anyone know how many current players use it? This particular bat was a 2001 Rich Hackett RC1. I've seen two Paul Molitor P130's recently that both feature the same knobless style, including one that's up on ebay right now.
But that's about it in terms of 'recent' bats. If he reads this, perhaps BMH could give anecdotal stats for how frequently players these days request bats that don't have a truly defined knob.
Compare the two knobs from SAM bats here: