Why is plato called plato if his real name is aristocles?

According to Diogenes La�rtius, the philosopher was named Aristocles after his grandfather, but his wrestling coach, Ariston of Argos, dubbed him "Platon", meaning "broad," on account of his robust figure.[21] According to the sources mentioned by Diogenes (all dating from the Alexandrian period), Plato derived his name from the breadth (platyt�s) of his eloquence, or else because he was very wide (plat�s) across the forehead.[22] In the 21st century some scholars[citation needed] disputed Diogenes, and argued that the legend about his name being Aristocles originated in the Hellenistic age.[c]