NY Yankees Prodigy Clint Frazier: Reggie Jackson Mentors Me ... We're Froyo Bros (VIDEO)

The NY Yankees are FIRED UP about their big 22-year-old outfielder Clint Frazier -- who says Reggie Jackson is personally mentoring him ... even taking him out for froyo!  Frazier was the #5 overall pick in the 2013 MLB Draft -- and some…