Manchester United made a critical mistake over the summer, and it is very likely to cost them millions. It has been a disappointing start to the season under Michael Carrick, whose magic from last season looks to have burnt off rather quickly.

United have won just one of their first Premier League games, and they go into a tough-looking away clash with Leeds United on Sunday on the back of a Champions League defeat to Atletico Madrid. Carrick is coming under serious pressure, and there is even talk that he could be sacked if things don't go the way of his side this weekend.

It's a situation that many saw coming, and that's because United have been here before with former players they show a little too much respect to, such as Ole Gunnar Solskjaer.

Picking up a broken team and guiding them to a strong end to the season is very different from overseeing a full season, and United need to start understanding that. They can use ex-players to galvanise their team when things don't go right, but it doesn't mean they have to give them the job full-time. They have to be more ambitious than that, and they have to start making decisions like one of the biggest clubs in the world, which they are.

Clubs of that size must be ruthless when it counts and appoint people to positions with a clear track record of success at a high level. That should be the only way anyone gets a high-level job at Old Trafford. No exceptions.

United should have appointed Silva

United decided not to get involved in a summer of managerial recruitment when several top and up-and-coming managers were available. The likes of Andoni Iraola - albeit briefly - Oliver Glasner and Marco Silva were all available due to leaving their respective Premier League clubs.

All of them found new jobs, and Silva ended up at Benfica having enjoyed an impressive run at Fulham, who are rock-bottom following his departure. Silva has vast Premier League experience and a style of play that translates to all levels, concentrating on being defensively sound, which United could have done with this season amid a lack of investment at the back.

Pep Guardiola said as recently as February:

“Marco is one of the top, top, top managers I face. Destined to be one of the top in a few years for sure.”

The former Everton boss ended up joining Benfica, who are third in the league, but they have beaten AC Milan away from home in the Europa League and thrashed Celtic in their second game in that competition this week. Silva's start has included 12 wins from his first 16 games, only losing twice.

Silva's managerial win% record by club

• Estoril - 46.6%
• Sporting CP - 58.5%
• Olympiacos: 79.2%
• Hull - 36.4%
• Watford: 30.8%
• Everton - 40%
• Fulha: 43.7%
• Benfica - 75% (Present)

Silva is due a shot at the big time, and it will be interesting to see how he managed a big club at Benfica. United should have given him that opportunity, and had they done so, they would have avoided the likely millions of pounds they will have to spend to hire Fabian Hurzeler from Brighton whenever they decide the Carrick experiment is the latest to have failed.