My favorite underrated Yankee prospect is 21 year old shortstop Thairo Estrada. He only recently cracked the MLB top 30 Yankees Prosects list even though he has been hitting well over .300/.375/.400 all season while playing for shortstop and second base for AA Trenton Thunder. If you look at Estrada's production throughout his four previous minor league seasons, this performance is not coming out of nowhere, either; his career slash line is .290/.354/.392.
An additional sign that Thairo is no fluke is his BB% and K%. Over his career he has a BB% of 7.5% and a K% of 12.4%, totaling 100 walks and 166 SOs. Those rates might be improving, too! This year, Thairo has 21 BBs and only 28 SOs, good for rates of 7.7% and 10.2%, respectively. There was a strong argument that Estrada was outperforming Torres when Torres got called up to AAA Scranton Wilkes-Barre.
I am not arguing that Estrada will be better than Torres, but that Estrada has been grossly underrated. He might not develop much power, but his hit skill is elite and he plays multiple premium defensive positions. He will be Rule-5 eligible at season's end and I think the Yankees need to prioritize protecting him over hyped-up guys like Jorge Mateo, who still somehow sits in the #4 spot on MLB's Yankees Prospects list despite regressing in production every year of his minor league career.