When Manchester United paid Arsenal £24 million for Robin van Persie in August 2012, eyebrows were raised because of the Dutch striker's advancing years and checkered injury record. Not to mention the fact the Red Devils didn't appear to require another forward; they had more pressing concerns, such as recruiting a new top-class central midfielder, after all.
Ferguson wouldn't usually have given the green light to such a deal - but Van Persie was the Premier League's best striker at the time and Manchester United had been beaten to the title months earlier by local rivals Manchester City by virtue of goal difference.
Keen to make sure that wouldn't happen again, and knowing this would be his final season in charge of the Red Devils, Ferguson went all in and brought Van Persie to Old Trafford - fully aware, surely, that within a few seasons the striker would have entered the early stages of decline.
Van Persie enjoyed dream debut campaign
Van Persie enjoyed a magnificent debut campaign with Manchester United, helping the Red Devils secure their 20th league title by scoring 26 goals in 38 Premier League matches.
It could not have worked out any better for the Dutch striker, who tarnished his reputation as an Arsenal hero in a bid to win some overdue silverware at Old Trafford.
Van Persie clearly enjoyed a fantastic working relationship with Ferguson, but since the Manchester United legend retired, the 31-year-old forward has not looked the same player.
Van Persie affected by Ferguson departure
Judging by his body language it seemed clear that he found the experience of working under Ferguson's successor, David Moyes, to be a miserable one. Admittedly Van Persie endured an injury-hit campaign - he made 28 appearances in all competitions - but he looked a shadow of the player we all witnessed dominate months earlier.
He appeared less sharp, less powerful, less clinical and, most worringly, less motivated. Had his decline as a footballer arrived earlier than expected?
That assumption was briefly put on hold during the World Cup finals in Brazil. Van Persie scored four goals - the same tally as tournament superstars Lionel Messi and Neymar - as the Netherlands reached the semi-finals.
Van Persie dreadful so far this season
But Van Persie has been very disappointing since returning to action with Manchester United this season, even though his favoured coach, Louis van Gaal, is now in the Old Trafford hot-seat.
Recent reports suggest that the seemingly untouchable relationship between Van Persie and Van Gaal has become increasingly strained over the past few months. And it could well reach breaking point over the forthcoming weeks.
Radamel Falcao is a better striker
Van Persie insists that he is unfazed by the arrival of the world-class Radamel Falcao - but he soon will be.
Falcao should be handed his first Manchester United start against Leicester City on Sunday, and it's likely to come at the expense of the out-of-sorts Van Persie, who deserves to be dropped to the substitutes' bench thanks to his abject displays.
Rooney, as the team's captain, is not about to make way - especially after his impressive performances for England and United over the past seven days; while Juan Mata should retain his place as the team's playmaker having scored a superb eight goals in his last 10 Premier League outings.
Van Persie can't play in a front two
Van Persie flourished for United and Arsenal while playing as the team's most-advanced forward. But Van Gaal's system favours two strikers working in tandem, and the Dutch forward simply doesn't look suited to playing this role.
Both he and Falcao are out-and-out goalscorers. As we saw during Sunday's 4-0 win over QPR, Falcao will always - always - look for the shot first, second and third before even considering the pass when in a goalscoring position.
The same applies for Van Persie, who is no longer the Red Devils' best centre-forward but still earns a whopping £250,000-a-week deal.
Falcao should start in place of the Dutchman this weekend - and it's hard to see Van Persie winning his place back from the world-class Colombia international.