DH (serious baseball guy) says that a couple of years ago, the Red Sox decided to grow their beards out like a a good luck charm (baseball players are very superstitious). They were last in 2012. the next year, they were doing really well, so they decided not to shave as long as they kept on winning. They made it to the World Series & won in 2013.
In the 70s, the Oakland Athletics did the same with mustaches (lol they won the World Series, too). Back then, the leagues didn’t allow facial hair at all.
Baseball players are funny guys. DH thinks this is just a fad.
The 70’s A’s grew mustaches because Charlie Finley had a mustache promotion night and he gave a bonus to any player that grew one as a tie-in to the promotion.