I had to look it up, I don't see any evidence that Blizzard's Michael Ybarra [1] is related to Joe Ybarra [2] who produced The Bard's Tale (1985). So he apparently has nothing to do with Ybarra's Mystical Shield (MYSH) and Ybarra's Mystical Coat of Armor (YMCA).

I can't even tell you how many times I typed YMCA on my Apple IIc, playing Bard's Tale. It was a lot, though.

[1] : https://en.wikipedia.org/wiki/Michael_J._Ybarra [2] : https://en.wikipedia.org/wiki/Joe_Ybarra