Dubbed the 'worst Welsh team of all-time' when he took over in 2001, Hughes eventually led his country to the brink of this summer's European Championship finals.
Unfortunately, they failed at the final hurdle, blowing it at home against Russia in the Euro 2004 play-offs.
Simon was a key figure throughout Hughes' reign - indeed, Hughes gave him his full international debut against Ukraine in March, 2001 - and the midfielder isn't surprised he's starting to turn things around in the Barclays Premiership at Blackburn Rovers.
"First of all, you looked at him and it's Mark Hughes and for Wales, he was one of our greatest players ever, so that was enough to start with," reflected Simon on Hughes' time with Wales.
"You wanted to impress him and do all you could and I would say that even more so for Wales because we don't produce that many world-class players and he's definitely one of them. You looked up to him straight away.
"He was learning the managerial ropes and got better and better as he went on.
"When he joined we were in the middle of a really bad run and we were being labelled the worst Welsh team ever.
"But we were always confident of what we were doing and we soon went on the best run a Welsh team has ever had. That says it all really. He turned everything around and took it as far as it could go.
"There was always the feeling he was heading for a club, especially when we had that great run and he was always being linked with jobs.
"I know he wanted to do really well for Wales and he did that but the day in, day out stuff is where he's going to learn what it's all about. Having played for Blackburn and living up there, it's a perfect move for him."
Always explosive during his playing career, Hughes appears as a softly-spoken, thoughtful manager.
Was that always the case? "Generally he was quiet but you saw glimpses," Simon revealed. "It's different at international level because you are not with players day in, day out but we knew what we had to do and if we didn't, he told us about it.
"He certainly has that streak in him and there is a line you don't want to cross. He has the credentials to be one of the top managers."
Simon Davies never doubted that Mark Hughes would step into club management after his stunning start with Wales.