Mauricio Pochettino switched Eric from his right-back and central defensive roles in a successful debut season in 2014-15 into the holding position last pre-season. He didn't look back, starting 50 of our 53 games in all competitions.
His performances led to an England call in November and he's appeared in every game since, earned a starting place in Euro 2016 and capped it all with a stunning free-kick in the opener against Russia. He's set to be there again as England bid to top the group against Slovakia on Monday.
Eric's displays have come as no surprise to Ledley, who knows a thing or two about switching from defence to the holding midfield role - he was employed there for most of the 2003-04 campaign before switching back to central defensive duties.
"The first time I saw Eric play in that new role was in pre-season and he impressed me straight off the bat in that first game," said Ledley, who earned 21 caps for England and played in the 2004 European Championships.
"He looked settled immediately and we all knew from that moment he could play in that position.
Below: Ledley in action for England against France in Euro 2004
"He's probably surprised a few people with how well's he's done but he had a good footballing education in his younger days at Sporting in Portugal and he can clearly play in numerous positions.
"What I really like about him in there is that he's a big man but he can get around the pitch. We looked at the game against Wales and the job he'd have to do with Gareth Bale drifting around in those dangerous pockets and protecting the back four and he was great in there.
"He has that recovery power where if he gets on the wrong side, he can get back in with his running, he can make tackles and he's defensive-minded as well, so he's a huge bonus for the back four.
"He's got it all in that position. He has to be one of the first names on the teamsheet now and that's how important he is to the England set-up."