Wilson first let his whiskers grow while recovering from injury early in 2010 as a shared joke with team-mate Sergio Romo.
But what started as a bit of fun turned serious as the facial furniture began to grow on him - in every way. Wilson's form, and that of his team, were so good that he vowed not to shave until the end of the season, and the Giants went on to win the World Series with the man himself throwing the winning pitch.
His beard back then was a mere shadow compared to what the 29-year-old is now sporting, however, and his carpeted chops inspire our look at sport's greatest beards.
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Cricket's Hashim Amla: The South African delivers with an unforgettable combo of bald head and a chin hedge that could house several small mammals.
Rugby's Sebastien Chabal: Was once the world's best-paid rugby player, but clearly didn't like spending any of his dosh on personal grooming.
Football's Socrates: The Brazilian legend - who sadly passed away last year - was famous as a brilliant midfielder, a qualified doctor, a political activist and a wearer of one of the coolest beards of all time.
F1's John Watson: Having to wear a thick, heavy helmet for two hours in often sweltering conditions means racing drivers need true dedication to wear facial hair. That instantly gives the British Lotus, Brabham and McLaren driver extra kudos - almost as much as he earns for once having won from 22nd on the grid.
Golf's Lucas Glover: The 2009 US Open champion's facial hair got so shaggy during 2010 that Justin Rose tweeted a picture of him with the caption: "Winning a US Open: so easy a caveman can do it."
Football's Alexi Lalas: The American superstar and Billy Connolly lookalike did more for ginger beard-wearers than anyone since Frederick Barbarossa.
Cricket's WG Grace: He might be the man who made cricket the game it is today, but he remains equally famous for a beard that is higher, and more picturesque, than the Angel Falls.
Football's George Best: The Northern Irishman was far too busy winning European Cups, nutmegging Johan Cruyff, wooing models and drinking Manchester dry to worry about things like shaving.
American football's Brett Keisel: He might have two Super Bowl winners' rings taking pride of place on his mantelpiece, but Keisel's remarkable beard is probably his finest achievement. His facial hair has its own Facebook and Twitter accounts, and he has bragged that he is the owner of "the greatest beard of all time".
Tennis's Bjorn Borg: The Swedish tennis legend-turned-underwear impresario won several of his Wimbledon crowns while sporting the sort of beard favoured by his compatriots in ABBA.