With his contract running down at Emirates Stadium, Sanchez opted to swap north London for Manchester.
As he headed out of the capital, Mkhitaryan went the other way after falling out of favour at Old Trafford under Jose Mourinho.
Neither has made the expected impact in new surroundings, with Sanchez having sparked talk of another possible move after contributing just five goals to the United cause.
Former Arsenal midfielder Paul Merson told Sky Sports of the Chilean’s struggles since leaving the Gunners: “I hope we see the old Sanchez, but I don't see the confidence or the hunger in his eyes anymore.
“The first thought that used to come to mind when you mentioned Alexis Sanchez was that he worked his socks off, he put a shift in.
“Sanchez has lost that hunger and it's a shame. It's sad because he was good.”
Another ex-Gunner, Charlie Nicholas, agrees with that assessment of Sanchez and feels Mkhitaryan has fared no better during his 12 months at Arsenal.
He added: “I think that’s fair. It’s the same frustration for Arsenal with Mkhitaryan, who has suffered the exact same thing – just doesn’t know what he is doing even though he is a clever footballer.
“It pains people to watch [what is happening to] Sanchez.
“He was a street fighter, a warrior, with talent. He is now staying rigid on the left and he gives the ball away so often it’s frightening, the level he is playing at.
“He will have an occasional burst of games but never as consistent as what he's been in the past.”
Sanchez has taken in 20 appearances for United this season, with his most recent drawing plenty of criticism.
He stepped off the bench during a Champions League last-16 encounter with Paris