Mike Catt believes England can still use Wayne Smith's coaching expertise to their advantage.
Catt has agreed a short-term deal to become Stuart Lancaster's backs coach for the tour of South Africa in June.
Former New Zealand head coach Smith turned down a longer-term role in the set-up for family reasons.
"I still don't know why Stuart can't tap into Wayne's knowledge anyway," said Catt, a member of England's 2003 World Cup-winning side.
"[Former New Zealand coach] Graham Henry is still doing stuff around the world and I think Stuart has a good enough relationship with Wayne to be able to do that."
Catt, 40, will leave his coaching job with London Irish after their final Premiership game of the season this weekend to join England.
He will work alongside Lancaster and forwards coach Graham Rowntree.
"I've got a two-month window that I need to make sure I get things right, make sure I complement Stuart and Graham in everything they do and that I get the players on board too," Catt said.
"Stuart has given me this opportunity. I just want to take it with both hands."