That’s the opinion of former Liverpool managing director Christian Purslow, who claims the deal was a “once in a generation opportunity”.
The Chile international was out of contract at Arsenal at the end of the season and was expected to join Manchester City after a deal was almost agreed in the summer.
But Manchester United made a list-ditch attempt to steal Sanchez from under City’s noses with a bigger offer which included Henrikh Mkhitaryan.
City were unable to match United’s offer with Jose Mourinho pulling off one of the coups of the January transfer window.
And Purslow suggests Arsenal would have been delighted with the package they received from the Red Devils.
“We will never quite know the sequence of events that led to that potential transaction winding away into a United purchase,” Purslow told Sky Sports.
“It has the look from the outside, I don’t know this to be true, that Arsenal out of nowhere had their dreams come true.
“Rather than being in a unilateral discussion with City taking their best player nearly on a free, they had a little auction going when Mourinho and Antonio Conte both spoke up in early January that actually getting Sanchez was a once in a generation opportunity to buy a top player for not much money down.”
He added: “I think Arsenal suddenly had a little auction going. I suspect when Sanchez’s agent said to Manchester City’s executive team you might have to improve my deal up a bit because United are here – that [would have] felt like a breach in trust,” he added.
“They thought they had a handshake deal at best. I bet they were very angry about that and I suspect they thought actually let’s walk away from this deal leaving Manchester United to sweep him up.
“Brilliant outcome for United, pretty good outcome for Arsenal on balance but I suspect not a very happy camp at City around the way that deal was conducted.”