The beard has magical powers.
When Houston Rockets star James Harden needs special powers, he can transform into a Super Saiyan:
If anything, his replacement beard should be even longer.
It is indeed more than a legend. As the Dragon Ball Z Wiki page says, one can turn into a Super Saiyan "in response to a need, not a desire."
Harden isn't the only one in the sports world who has powers. Miguel Herrera, former club America coach and current manager of Mexico's national team, also has the ability to transform: