Roeder sa tidligere at Dyer løp rundt 1,2-1,3 mil pr kamp. Han er visst ikke alene om det.
"If you think you're going to leave a club when you don't really want to and then you're asked to come back, he will reflect on that as a turning point. It was a crossroads for him.
"It was such a disappointment for him at the time and he had to decide how he was going to handle it. He had to think `Am I going to lie down and cry about it? Or stand up and fight for my position?'
"I would say that one day he will look back and say that it was a crossroads in his career, where he feels he became a man, where he showed maturity. The easiest thing for James would have been to come back and sulk. But he didn't do that, he came back and carried on training as hard as anyone I have ever known."
O'Neill's loss has been Roeder's gain and, when Milner lines up against the Irishman's Aston Villa at St James's Park tomorrow evening, it will be as one of Newcastle's most important players.
"For someone who was so concerned about not getting enough games, he has ended up playing far more than anyone else," said Roeder of a player who has made 36 first-team appearances already this season.
"I am full of praise for the attitude he has shown and his maturity on that day. He could have remained a young man and shown a bad attitude, but he obviously decided that wasn't for him and he decided to knuckle down."
With three goals in his last five games, Milner's status as a Gallowgate favourite is secure and, having pinpointed the hard work the industrious wideman puts in as the key to his recent success, Roeder does not begrudge him the praise he continues to attract.
"I always tell the lads about Frank Lampard, who deserves everything he has got because of the effort he puts in," he added. "When I was at West Ham, Frank never ever went in after the main training session and James is the same, he will always do 15 or 20 minutes more.
"When James looks back on his career, he will look at the day he went down to Aston Villa to sign and came back hugely disappointed as a turning point," said the 51-year-old.
"James is always working on his finishing and those three strikes he has produced in our recent games haven't come as a result of sheer luck - they have come about thanks to sheer hard work.
"We have the Amisco (computer) system and we look at every game and how far the players are running and he is very rarely beaten by anyone in the Newcastle team. He is doing over 12½ kilometres every game. One or two of the others are getting around 12, but in terms of the amount of ground covered, James Milner wins the running stakes every time."