Sir Alex Ferguson has nothing left to prove. Everyone knows this. And if reports that suggest he was recently in New York speaking to Pep Guardiola about Manchester United are to be believed, the man himself knows it too. Still, this season has the potential to be one of the man’s finest, with possibly the stiffest challenge he’s ever faced.

Manchester City have had more financial power than United since 2008. As soon as Robinho turned up, Fergie must have known this was coming. A couple of seasons to get the spine of a decent team together and the right manager in place and the blue half of Manchester were title contenders, finishing third behind United and Chelsea. Then of course, after last season they finally had a legitimate claim to be greater than the red half.

Are they? Probably not, United had their excuses last season just like City had theirs the season before. Manchester United had the most days lost to injury in the Premiership, including serious injuries to key players such as Vidic, Nani and Rio Ferdinand. And the title still went to goal difference. This season, with both clubs spending and strengthening, will probably be the decisive one in terms of where footballing power truly lies.

Which makes United’s transfer dealings so much the odder. Five players in, Nick Powell and Angelo Henrique most likely ones for the future both being 18. Two forwards and a 23 year old Dutch left back never capped for his country. Of course United fans, (and people in general), may point out that those two forwards are two of the very best, and indeed they are. (Full disclosure: the author is a Liverpool fan and, despite detesting United, thinks Kagawa is tops.) The question is, did United need them?

Ferguson said that the arrival of Van Persie and Kagawa means that “the title certainly be lost on goal difference again”. The problem with that logic is that Manchester United had 89 points and 28 wins last season, quite the achievement especially with their injury problems. They scored 89 times, second highest in the division, and weren’t just flat track bullies. Eight were put past Arsenal, three past Chelsea and four against Everton. Ferguson quite slyly has seemed to forget that goal difference can also be improved by conceding less. Blackburn, City, Everton, Chelsea and Newcastle all scored three or more against the defending champions.

When fit and on form, Nemanja Vidic and Rio Ferdinand are one of the best central defensive partnerships in the world. Their contrasting styles mean that United are comfortable both playing from the back and defending deep in their own box. However, they’re both in their 30s and Ferdinand especially has been fragile recently. With Ferguson looking to have more of a technical, passing based midfield the center-halves have less protection in front of them and have to be even more solid. This hasn’t been the case. United have conceded in every game they’ve played thus far, and their defensive options look even thinner than last year. Michael Carrick was even pressed into service against Everton and his failure against Felliani has been well-documented. Vidic appears ring-rusty after a long layoff and had an own-goal against Fulham while even the old firm of him and Ferdinand looked weak against Southampton. Neither De Gea nor Lindegaard are top class keepers and the shaky displays in front of them are unlikely to inspire confidence. United’s relatively easy fixture list at the start of the season has meant that these lapses haven’t cost them but fixtures are going to pile up soon and the squad could be exposed.

In fact, when thinking about United the forward line appears to be the area that needs the least work. If a central midfielder or a fullback were bought no eyebrows would have been raised but the side are flush with attacking options, even with the departures of Dimitar Berbatov and Michael Owen.

Ferguson has said before that he rarely lines up in a straight 4-4-2, preferring to have a forward drop off to link midfield and attack, but early this season his side have looked to play in a 4-2-3-1. A clear double pivot in midfield and Kagawa in the hole behind the striker mean that United look quite graceful when they have the ball, but it seems a case of trying to fix something that wasn’t broken.

Perhaps Van Persie was just a big name signing made by the owners to placate a fan base that seems uncomfortable with the direction the club is heading, but Ferguson by all accounts looks pleased to have him. There’s a valid point of view that states if a top player becomes available, a manager should buy him and figure the rest out later. But with the club’s glaring need for cover in the heart of defense, one has to wonder if Manchester United spent their transfer budget in the right way.