London Irish head coach Tom Coventry hopes foreign "veterans" in the Premiership will not harm the development of young English players.
New Zealander Coventry was speaking after South Africa flanker Schalk Burger agreed a move to Saracens.
He questioned if older foreign players would harm home-grown development.
"With every veteran entering the game, those sorts of players push somebody down the pecking order," Coventry told BBC Radio Berkshire.
Coventry also mentioned Northampton's South Africa legend Victor Matfield, 38, as another player in the same category.
"You only have a very limited period as a young player to get the experience you need and to play," he added. "It would be a concern for English rugby.
"I've no doubt those players would add value, but when you're trying to develop your own players from within your country, I don't know if it's going to be a helpful scenario going forward.
"Rugby is still a young man's game. I think we have to be careful we don't end up looking at greener pastures all the time and not take stock of what's on our own doorstep."