The retired Ferdinand recently described Blind, this season playing in central defence, as United's "weak point" in the belief that he is playing out of position, and Koeman - like Ferdinand among the world's leading defenders while at his peak - agrees.
United on Sunday visit Southampton in the Premier League hoping to recover from Tuesday's Champions League defeat at PSV Eindhoven.
Blind could yet be moved to left-back to cover for Luke Shaw - formerly of Southampton - who has suffered a broken leg, but even if he plays in that more familiar position Koeman has highlighted him as a potential target for his team.
"On one side I agree [with Ferdinand] about his position," said the Southampton manager, who played alongside Blind's father, Danny, for the Holland national team.
"I think he can play very well out of that position but he's not really a strong defender physically
That's sometimes the problem
He has a lot of other qualities out of that position that can be very positive for the team.
"It's our job to analyse opponents and if he plays left or as a centre-back we can do some movements in attack with crosses
We know that (Southampton striker Graziano) Pelle is very strong and normally he's stronger than Blind is or stronger than [United's Marcos] Rojo is."
Among United's strengths this season has been the promising Memphis Depay, recruited for £31million from PSV in the summer a year after Koeman first sought to bring him to Southampton.
"When he was in the first team of PSV he was showing his qualities," said Koeman
"He is physically strong and fast and is clinical to score goals
"He had a great season and I think it was the right moment to move from Holland.
"PSV would not sell a player like that to Feyenoord [who Koeman once managed] but I was interested in him when I came to Southampton
In that summer we contacted the agent, who is also the agent of my brother [and assistant, Erwin] so it was easy.
"We showed interest but they said he would stay in Holland another year and then maybe he would like to move.
"We knew if interest from big clubs comes along, we don't win
That is normal
I think he will be a success if he keep his feet on the ground.
"[Southampton's interest] was in pre-season of my first year
They said he would stay in Holland and then after that maybe he would take a decision to move
That was the case.
"If you can move to United, Chelsea, Bayern [Munich], Real Madrid, you choose that
Not Southampton."
Source : PA
Source: PA