Erik ten Hag has worked with Martinez at Ajax for the past few years. He knows his strengths and weaknesses and will now begin to integrate him into his team throughout the remainder of pre-season.
In fact, there is enough evidence to suggest the Dutch coach started to make adjustments for the Argentine weeks ago. Before Martinez had even agreed to sign, Ten Hag seemed to be opening up a space for him.
For most of his career at Old Trafford, Harry Maguire has been deployed on the left of a two-man centre-back pairing, despite having a preference to use his right foot. The English defender didn't experience the strongest campaign last season, with Ten Hag even questioned following his arrival in Manchester whether Maguire would retain the captaincy.
Upon inspection of the United during the summer, Ten Hag's analysis identified how the team lacked balance and structure in certain departments – and he's stated as much on a number of occasions – with many of those issues stemming from the lack of left-footed options in the team.
United's centre-back options prior to Martinez's arrival – Maguire, Victor Lindelof, Raphael Varane, Phil Jones and Eric Bailly – were all right-footed. Nemanja Matic and Juan Mata were two left-footed players further forward, but both departed the club this summer.
Excluding Martinez, the only established 'lefties' in the current United squad are Alex Telles, Luke Shaw, Fred and Amad. Some coaches, including Pep Guardiola, believe footedness has an impact on balance and building passing moves from the back in particular.
After signing Aymeric Laporte in January 2018, the Manchester City boss said: “Its so important to have a left-footed central defender. He helped us to make our build-up and when the ball comes from the right, he immediately controls to the left and plays it to Leroy [Sane] – that is quicker than we would play with a right-footer in that position.”
Mikel Arteta, Guardiola's former assistant, is another believer in the importance of left-footed central defenders. The first signing made by the Arsenal boss upon his appointment at the Emirates was Pablo Mari, largely because the Brazilian was a left-footer.
United have not benefited from a left-footed player at the back for some years but in Martinez, they have acquired one, with Maguire's position consequently tweaked at the beginning of pre-season.
In each of his friendly appearances against Melbourne Victory, Crystal Palace and Aston Villa, Maguire has been fielded on the right of a two-man pairing rather than the left.
Telles has even accumulated some minutes as a centre-back in pre-season, purely because of his favoured left foot and how that trait can impact proceedings in the eyes of Ten Hag.
With Martinez now announced as a sealed transfer, United will be able to push forward with what seems to be their prearranged plan to use Maguire, Varane or Lindelof on the right and Martinez on the left. It will take time to achieve, but Ten Hag is striving to restore balance at Old Trafford.
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