The transfer saga of the Winter window has reached its climax, as Alexis Sanchez has followed in the footsteps of Robin Van Persie before him to leave Arsenal Football Club and join Manchester United. Sanchez's departure has been the worst kept secret in football for a long time, so thankfully it's finally been completed. It's easy to feel animosity towards the Chilean forward due to the egregious circumstances on the run-up to his transfer, but it's worth recalling that the reason this anger is being felt is because he was often the Gunner's star player - a player that could arguably fit into any side in the world. With this being the case, his void may be a difficult one to fill.The difference between this deal and the RVP one is, rather than a transfer fee - and an odd video announcement featuring a piano - Arsenal are receiving a player in return: Henrikh Mkhitaryan.Mkhitaryan is a winger/attacking midfielder that can both score goals and set them up; he’s 29 years old and he’s the only Armenian international to ever play in the Premier League. Upon having his transfer for the club confirmed, he tweeted that he was “Overjoyed and honoured to sign for the club I supported as a boy”.In a day where one of the best player’s to don an Arsenal shirt in recent times departs the club, a new era begins for Mkhitaryan, but there are two questions that need to be answered: why did it not work out with Manchester United and how will he fit into the Arsenal team. Mkhitaryan's time in a United shirt wasn't spectacular, but it had its moments. Arriving in the Summer of 2016 alongside fellow Mino Raiola represented players Paul Pogba and Zlatan Ibrahimovic, the diminutive Armenian had a stuttering start to his time in red. The stand-out performance in the early days of last season was no doubt the first Mourinho Vs. Guardiola Manchester derby, where Mkhitaryan's contribution was so poor that he saw himself subbed off at halftime and did not play a minute for 2 months.He made a case for himself to make a return to the side with some sterling Europa League displays, where the side were given a lot more freedom than they were in the league. This culminated in United winning this competition, with Mkhitaryan putting in a man-of-the-match performance in the final in Stockholm against Ajax.Following a great start to the current season that seen him register 5 assists in a free-scoring United team, he was axed once more and his season wasn't particularly noteworthy for the former Borussia Dortmund and Shakhtar Donetsk man - bit parts were common - so it's not surprising to see him moving on from Manchester United.So, where did things go astray for Mkhitaryan at United? The truth is, and it's quite easy to say in hindsight, is that he joined the wrong sort of team. Under his Dortmund manager, Thomas Tuchel, he was part of a team playing fast, organised football - not the first words that spring to mind when you think of Mourinho’s United. Playing as a front three alongside Marco Reus and Pierre-Emerick Aubameyang (also heavily linked with a move to Arsenal), and with Lukasz Piszczek acting as an overlapping full-back, Mhkitaryan had a frighteningly incredible season in the Bundesliga - registering 23 goals and 32 assists in 52 matches.In Tuchel's Dortmund side, Mkhitaryan was played in a wildly successful 4-3-3 formation. When given the opportunity to play for United, he was often deployed in the centre as opposed to his preferred position of winger (although some would argue that he is as happy playing down the centre, which could prove problematic if Mesut Ozil remains at the club) - in a 4-4-1-1 formation, with him occupying the place behind the striker (Ibrahimovic in the first season, Romelu Lukaku in the second).Picture this - imagine Mkhitaryan had never moved to United, and he was just about to sign for Arsenal to make his debut with a Premier League team. The excitement would be palpable, and he would be considered the perfect replacement for Sanchez; offering something different, but all the while, incredibly potent.The winger will be looking to redeem himself in English football - not that the need for redemption is necessarily his fault, his treatment at United was undeniably unfair - and Arsenal is the perfect place to do it.Currently Mkhitaryan represents a good signing. If his former teammate Aubameyang is also added during this transfer window, then there is the potential of a rejuvenated Arsenal attack. While it needs addressing, lets ignore the defensive positions for a moment. If Arsenal hold on to Mesut Ozil (who is no doubt going to be heavily linked with a move away over the coming days) there will be some interesting conversations to be had about formations.This season, Arsenal have opted for a 3-4-2-1 and 4-2-3-1 formation on alternating occasions, with both formations seeing their fair share of success and failure. So, can Ozil and Mkhitaryan be played together? My thinking would be that they can be, in the latter formation, although this may leave a lack of versatility on the flanks. However, having those two players behind you would be a dream come through for a striker, and could help someone like Alexandre Lacazette find the net on a more frequent basis. If the rumours about Aubameyang turn out to be true, then there are even more opportunities to play fiercely intimidating attacking formations, and there is depth to rear-guard the squad in case of injuries... at least in attacking positions.Considering the negativity that has surrounded the club in recent weeks, not counting the weekends win at Crystal Palace; more so the FA Cup exit, the loss at Bournemouth and Sanchez's exit, it's worth ending on a positive note. Now that Arsenal have signed the promising Mkhitaryan, if they can secure Aubameyang and hold on to Mesut Ozil, then this has been the club's best transfer window in years. It may not solve all the problems, but it does show indications of a necessary overhaul, and hopefully good things for the future.