Southampton manager George Burley feels Theo Walcott's career has gone backwards since he left the Saints for Arsenal in January.
If you move too early to a big club then it can be detrimental to your career
Walcott joined Arsenal for £12.5m but the 17-year-old has barely played since and he endured a frustrating time with England at the World Cup.
"For me, career-wise, it was the wrong choice for Theo to leave," said Burley.
"I think he's played one-and-a-half reserve games since he left Southampton in January."
Burley took over at Southampton in December 2005 and promised Southampton fans that Walcott was central to his plans.
But the club were left with no choice when a then 16-year-old Walcott demanded to leave.
Burley said: "It was a difficult situation when we sold him because there was nothing Southampton could do.
"He was a 16-year-old and he could walk out of the club any time he wanted to, so you are governed by that.
"Given the choice between Walcott and the money we'd have kept the boy, but you've got to go and reinvest when it's done.
"When the player and his representatives and his parents are saying they want to go to Arsenal, there's nothing you can do.
"If I were his parents I would have let him stay at Southampton, let him mature, give him time, and then let him move along."
I don't think [going to the World Cup] has done him any good because everybody has been talking about him
Former Ipswich boss Burley added: "I remember telling Richard Wright when I was at Ipswich before he moved to Arsenal that he needed another season to progress at Ipswich.
"But he went and nobody's heard of him for the last five years.
"If you move too early to a big club then it can be detrimental to your career.
"They sometimes get loaned out and you're never sure of their development.
"I hope it doesn't happen to Theo. He's a smashing lad, I know his dad well, but I think they are taking a big gamble when maybe you don't need to take a gamble."
Burley also thinks that Sven-Goran Eriksson's decision to take him to the World Cup has not helped Walcott's career.
Eriksson picked Walcott ahead of the likes of the more experienced Jermain Defoe and Darren Bent but chose not to use him at all in Germany.
Burley added: "Managers chose what they think is right, but players have to earn the right to get into the team.
"I'm sure there are one or two disappointed strikers out there who had earned the right and didn't get the opportunities for the World Cup.
"Personally I don't think it's done him any good because everybody has been talking about him.
"It's not the boy's fault he got chosen or that he has not played Premiership football.
"I feel for the boy a little bit because I think it was undue pressure he was under and I hope he kicks on.
"He's a very dedicated boy and a strong character and I'm sure he'll come through.
"Because given the right education, playing-wise he will be tops."