West Bromwich Albion's head of academy recruitment Steve Hopcroft believed Izzy Brown could have been a "£40million player" revealing in 2016 that he was the "best we've lost."
Brown, now 21, left Albion's academy in 2013 at the age of 16 opting to make the move to Stamford Bridge with Chelsea but is yet to make any real mark in west London.
The attacking midfielder joined Leeds United last week on a season-long loan as he continues his recovery from a torn ACL in his latest stint away from the Blues having spent time at Vitesse, Rotherham United, Huddersfield Town and Brighton in recent seasons.
Hopcroft, who was speaking to the BBC in 2016, revealed he believed Brown to be one of the best youngsters the Baggies have lost during his time at the club revealing the midfielder has the potential to be a world-class player.
"He made a decision and his parents made a decision that West Brom wasn't for them at that time," Hopcroft said. "I wasn't party to it, but I know really good offers were made.
"He's the one that got away for me. The manager at the time, Steve Clarke, was ready to make him an integral part of the team.
"We had a potential £20-£30-£40 million player that the fans would have loved, full of flair and skill. He could take on six players from his own half and score.
"I was bitterly disappointed, as was everyone in the Academy. He's still potentially a world-class player, the best we've lost, without a shadow of a doubt."