Sam Burgess was "made a scapegoat" by rugby union during his ill-fated switch from rugby league, said former Great Britain coach Tony Smith.
Burgess was a controversial pick in the England rugby union squad that was eliminated at the group stage of the 2015 World Cup.
He said his heart "wasn't in" rugby union and was stung by criticism from ex-players.
"I think it was a pretty dark time psychologically for him," said Smith.
Former England rugby league captain Burgess announced his retirement from playing on Wednesday, because of a chronic shoulder injury.
Burgess, 30, is one of rugby league's biggest names and had played for South Sydney Rabbitohs in Australia's National Rugby League since 2010.
He previously played for Bradford Bulls and played 23 matches for England, and two for Great Britain.
He switched codes to join rugby union side Bath in 2014 and was fast-tracked into the England team, earning five caps, but returned to rugby league after just a year.
The 2015 World Cup was seen as a nadir for England's rugby union team and four years later they have reached the World Cup final.
Hull Kingston Rovers head coach Smith, who gave Burgess his Great Britain debut, told Radio 5 Live: "I think he was made a scapegoat by a sport that used him and chewed him up to some degree. Sam was hung out to dry.
"I thought he held a great account of himself in rugby union, to play at the highest level and do such a good job as he did - not many people could achieve that, and I know there wouldn't be many that could come the other way and do it."
Smith added: 'He's one of my most talented rugby league players I've ever coached - also one of my most impressive guys that I've coached as a human being."