Moses made a bright start to his Hammers career, but he has struggled to make an impact more recently.
And Etherington says that the winger’s lack of consistency is now becoming a worry.
"I think he started well at West Ham, but he's gone a bit quiet to be honest," Etherington, who used to play for West Ham, said.
"I was really excited by his signing personally, but he hasn't really done himself justice yet.
"Like he was at Stoke, I think he's one of those players with loads of natural talent and it's just a case of doing it consistently."
Moses’ failure to perform to a consistent standard has been one of the major issues in his career.
The Nigerian is one of the most threatening wide-men in the Premier League on his day, with his pace and power making him a nightmare to mark.
However, he has a tendency to allow his levels to drop, and that has been one of the reasons why he has struggled to find a permanent home.
Moses has been loaned out by Chelsea for the past three seasons, and he has spent time at Liverpool and Stoke City prior to his move to West Ham.
Moses has made 11 appearances for Slaven Bilic’s, and he has scored once. He is currently out injured, meaning he will miss the Hammers’ match against Stoke at the weekend.