Dave, upon further research it appears that those MLB tags started showing up in 1982, since I saw an authenticated game used 1982 World Series cap with the MLB tag. I haven't seen anything that is from 1981 "for sure" that has the MLB tag, but I suppose it's possible. I believe it was 1982 when Sports Specialties joined the on-field MLB cap market and made themselves the first MLB "licensee", then New Era and Roman Pro quickly followed suit.