We have a winner!
The first person who posted the correct guess that what makes this glove special is that it is a left-handed model (and I am left-handed) and it is a Robin Yount model was Justin Cousson. Congratulations!
Being left-handed has complicated things all my life, not the least of which had to do with baseball glove choice. Finding this on eBay was quite a coup. Justin, get in touch with me so I can mail you your prize, a bunch of Robin Yount oddball cards, of course.