" was my first hunch as well, but Esau
in the Spanish bible is "Esau
". Another site suggested, without much conviction, that Esai might be a variant of Jesse
. But Esai is not in Hitchcock's Bible Dictionary (the definitive work on Biblical names), and Jesse
in the Spanish bible is "Jese".
Three 16th century English bibles I referenced (love that 'Net!) use the name Esai (2) or Esay (1) for "Isaiah
", so I'm pretty sure that's the derivation. How a Puerto Rican kid named Morales got the name is anyone's guess, but he WAS born in NYC...