#2 He beat generations to stay at the top
One reason why Sir Alex commands massive respect for his achievements is the longevity he displayed in his Manchester United career.
Of course, the fact that he managed the club for 27 years and lifted 38 trophies with the club makes him a footballing great in every aspect. But, what stands out is the fact that he managed to beat generations to stay at the top by building 4 different teams during his spell at the club.
First, it started with beating Blackburn in the early 90's. That was followed by Newcastle and then a resurgent Arsenal under Arsene Wenger.
As Sir Alex successfully saw off challenges from the Invincibles by winning league titles, another threat emerged in the form of Chelsea led by a young Jose Mourinho. But, even the Portuguese couldn't hold the Scot at bay, as Man United lifted the league title thrice in a row, followed by Mourinho's back-to-back league title triumphs.
Last but not the least, Sir Alex managed to fend off another threat to his throne, this time from filthy rich neighbours Manchester City. After the heartbreaking manner in which United lost the title in 2012, they bounced back to win it in the next year with a healthy 11-point lead at the top of the table.
And oh, how can we forget about Liverpool? He surpassed United's bitter rivals as the most successful club in the history of English football during his trophy-laden spell at Old Trafford.
Managing in different leagues is a challenge no doubt, as a coach has to adapt to different styles of play and deliver the results. But, during his 27 years at the club, Sir Alex proved that facing different challenges while staying put requires an equal amount of dedication and determination to succeed.
His ability to adapt to changes by trying out different ideas enabled Manchester United to stay at the top, no matter whichever club they faced during his spell at Old Trafford.