In discussion with reporters ahead of Wednesday's Champions League visit from Atletico Madrid, Flick said Davies has yet to reach the same standard from a breakout 2019-20 season.
"Alphonso's form dropped a bit," Flick said, courtesy ESPN UK's Stephan Uersfeld. "But he gets all our support. We benefit from his pace, his energy. It's important he gets back on track."
Hernandez, who joined Bayern for a club-record €80-million fee from Atletico in 2019, has started three of four matches in the league and the Supercup and DFL Supercup finals in place of Davies. Hernandez was also named to Flick's largely youthful starting XI for the cup tie with FC Duren.
Davies shone last season at left-back after injuries to Hernandez and others forced the winger to learn a new position on the fly. The 19-year-old was heralded for his contributions as part of a historic treble-winning campaign, and is among a shortlist of favorites for the annual Golden Boy award.
Flick is optimistic Davies will again find his footing, adding: "It's a bit normal to see a young player go through such a spell following an incredible season. We will support and help him."