Antonio joined West Ham from Championship side Nottingham Forest in the summer of 2015.
In recent months, though, the Englishman has been superb and has established himself as an important player in Slaven Bilic’s side.
Gray has been impressed with Antonio and told Sport360.com: “And who would have thought Michail Antonio would come from Nottingham Forest and have the impact he has had in the last three months? He was an inspired signing.”
Antonio has scored six goals and created 16 chances in 20 Premier League appearances for West Ham so far this season.
The winger has a pass accuracy of 66% and a shot accuracy of 45%, and has won 30 headers, 32 dribbles and 21 tackles.
Despite being impressed with West Ham, Gray has predicted that West Ham will not finish in the top four of the Premier League this season.
Speaking ahead of the Hammers’ Premier League game against Arsenal at the Boleyn Ground on Saturday afternoon, Gray told Sport360.com: “They will keep pushing on now but can they nick a Champions League place this season?
“Top six, yes, but I think top four is going to be out of their reach but that doesn’t mean they can’t make life difficult for teams like Arsenal.”
As it turned down, West Ham did make life tough for Arsenal, playing out a 3-3 draw after going 3-2 up following a stunning comeback from two goals down.
The Hammers are still in the running for the top four, but Manchester City have started to pick up points and they are likely to clinch the final Champions League spot.