Stoke suffered a thumping 4-0 home loss at the hands of Tottenham Hotspur on Saturday and the defeat means that the Potters remain rooted to the bottom of the table with just a draw from four matches.
Potters chief Coates has not been pleased with what he has seen of Stoke this season and has gone on to urge Hughes and his coaching staff to turn things around swiftly in the coming weeks.
Coates told the Stoke Sentinel: "We were ok for 40 minutes and were just about the better team, but then we were really poor and there's no disguising that.
"It was a really bad display.
"In the other games this season, nothing much had gone for us and I have previously said what I have said about those games. But against Tottenham we conceded a goal and then fell to pieces.
"There's no point hiding from that fact. It was a very poor performance.
"We haven't been scoring goals and then been going behind - and once we go behind we are not able to deal with it. I give an honest opinion. I'm sure that what I have seen Mark and his coaches have seen and they will want to sort it very quickly."
Stoke's next match takes place against 11th-placed Crystal Palace at Selhurst Park on Sunday.