The Netherlands international has struggled to settle at Old Trafford since joining from PSV and has started just once under Jose Mourinho, in the 3-1 win over Northampton Town in the EFL Cup.
Depay was left out of the United squad to face Fenerbahce in Thursday's Europa League clash in Istanbul, prompting further speculation that he could be offloaded in January, with AC Milan reportedly interested.
Advocaat, who was PSV head coach in the 2012-13 campaign, believes his former charge must consider his future as he is "too good to sit on the bench".
"The potential is there for him to be a good player," he said. "You cannot lose that, he has the quality to be a top player.
"But the problem for him is that there are so many quality players in that squad, so for himself it is important to start playing regularly at the age he is at.
"Otherwise, maybe he has to find another solution because he is too good to sit on the bench.
"I still believe in him. He has the right mentality, the right character to play for United, but there are so many options there. Regular playing time will help his progression."