Baboon hobgoblins

Sometimes we lose sight of our own history, even in hobbyist subcultures like that of D&D.  I was browsing the text—written by the man E. Gary Gygax himself—of The Official Advanced Dungeons & Dragons Coloring Album, published by Troubador Press and illustrated by underground artist from a similar van art semi-psychedelic fantasy scene as produced the Heavy Metal magazine.  If you haven't ever checked it out, you should.  Yeah, I know—it's a coloring book.  On high quality cardstock, with prose text by Gary Gygax, and an included mini-game.  It's worth checking out.  Plus, you can find high quality scans of the entire thing pretty easily.  Here, for instance.  But I draw your attention in particular to page 20 and its facing illustration; a battle between hobgoblins and gnolls.  The gnolls are described in a way that is very familiar to D&D players even today: "...hyena-looking humanoids.  These creatures are covered in greenish gray fur, with erect reddish gray manes. The gnolls' flat black eyes, dark muzzles and drab clothing mark them distinctly... clad in filthy brown pelts or scraps of clothing, and their shields are of dark blue, white, black, or deep green markings."

However... and I had forgotten this, because it had been a really long time since I looked at it, the description of the hobgoblins is very unfamiliar, and nothing at all like hobgoblins as we know them from today's D&D.  For that matter, the 1e illustration is more similar to today's conception of hobgoblins, but Mr. Gygax himself described them very differently here.  "On one side are hobgoblins, their baboon faces contorted with hate and fury.  Reddish brown and gray-black hackles raised, orange and red faces snarling, these creatures chop and stab at their opponents. One of the hobgoblins is so close that the elf can plainly see its blue-red snout, glaring eyes of bloodshot yellow-brown and bared fangs. The hobgoblins' yellow and red shields and black leather uniforms fill the entire left side of the arena."

I dunno; I find this whole thing strange and bizarre in the extreme. How did the hobgoblins end up being anthropomorphic savage baboons?  Where did that come from, and where did it go?