That’s the view of Gunners hero Paul Merson.
Manchester City made two bids for Sanchez this summer, with Pep Guardiola’s second offer reaching £60m.
However, Arsenal snubbed City’s approaches and kept their star man, who could leave at the end of the season on a free when his contract runs out.
The Gunners also signed striker Alexandre Lacazette and defender Sead Kolasinac.
And Merson says Arsenal had a below-par transfer window, claiming Arsene Wenger needed a defender, and the Gunners should have sold Sanchez.
“Arsenal haven't done enough in this window,” Merson told Sky Sports.
“They've bought a centre-forward when they already had one.
“They needed to buy defenders and they haven't done it.
“As we saw against Liverpool the other day, they just aren't good enough.
“I'd have sold Alexis Sanchez all day long.
“I doubt they'll get in the top four and they'll lose the £50m they would have got for him when he leaves for free.
“I think £35m for Alex Oxlade-Chamberlain is good money, but if they're letting him go then why not let Sanchez go as well?”
