Within two months, that early promise faded and things quickly started to go south. After three cameo appearances as a sub, Mikki was handed his first start in the Manchester derby. In a dissapointing team performance, Mkhitaryan was taken off at the interval and would not feature again for three months. There's an argument that, from that moment on, the narrative of his United career as a whole was set.
There have been moments of high class brilliance - his superb individual strike in Luhansk, that scorpion kick finish against Sunderland and his red-hot form in front of goal during United's run to Europa League glory last term. His goal in the final, which sealed the 2-0 result against Ajax, was his sixth of the tournament. It looked to have been his redemption and a turning point in his hitherto indifferent career with the Reds - the moment he won over his sceptical boss.
But in reality, he never really recovered from those difficult early months at United. It's always felt like he was operating under a shadow, knowing any small lapse would be seized upon by a manager who quickly lost faith in him. The final straw came in a woeful performance in a damaging defeat at Chelsea in November and that set the fire for Mikki's United future. He was hooked after an hour in which you barely even noticed he was there, and would start only more Premier League game. In the FA Cup game against Derby, in what turned out to be his final match in a United shirt, his confidence was shot to pieces. When he was again taken off at half-time, it was an act of mercy. Any remaining faith Jose had in Mikki had gone. When that happens, there's no way back and it's irrepairable.
On form, Mikki is a wonderful player - a swift, agile and technically gifted creator-in-chief, he's controlled in possession, neat and tidy with the ball at his feet and a highly effective playmaker. There's no doubting the talent's there but what's missing is his confidence.
It's almost certain that we've got the best from this deal, as for those of us that watched Mkhitaryan in Manchester, the idea of him being equal to Sanchez is very hard to believe.
Mikki will be fondly remembered for his pivotal role in us winning the Europa League last season and we wish him well in this new chapter of his career at Arsenal.