Cristiano Ronaldo returned to Manchester United this summer after a 12-year long wait. It was a move desperately awaited by United fans ever since the Portuguese left them in 2008.The Premier League was very different when Cristiano Ronaldo last played in it. Teams of any stature are now more tactically sound and can be very effective with their approach.Manchester United signing Cristiano Ronaldo was a massive boostManchester United have had their struggles ever since Sir Alex Ferguson retired but signing Cristiano Ronaldo was deemed to be a big step in resolving that. The Portuguese captain has time and again shown what a phenomenal player he is but the situation with the Red Devils is a bit tricky.Signing Cristiano Ronaldo was not something on the club's list before the summer transfer window opened. It was an opportunity grasped at the last moment and while it looked to be beneficial at first, it hasn't quite gone Manchester United's way. On that note, let's have a look at five reasons why the transfer has done more bad than good to the Red Devils:#5 Raised expectations and pressureReal Madrid v Sevilla - La LigaCristiano Ronaldo is a massive player and has achieved a lot wherever he has gone. Even when he arrived from Sporting Lisbon for his first spell at Manchester United, he was full of confidence and had pretty high standards to maintain.Since leaving United in 2009, Cristiano Ronaldo has gone on to achieve significantly more and at a rapid pace. His spells at Real Madrid and Juventus have been very productive for both him and the respective clubs. He has now established a certain standard and expectations are part and parcel of it.Noré Cerebróne@CerebroneThe final nail in the coffin of Ole’s time at Man Utd might be the signing of Ronaldo.No, not because he “doesn’t press” or all that stuff. No. Simply because you can no longer downplay expectations & get away with it. When you sign Ronaldo, standards/expectations MUST rise.9:25 PM · Oct 24, 20211568911The final nail in the coffin of Ole’s time at Man Utd might be the signing of Ronaldo.No, not because he “doesn’t press” or all that stuff. No. Simply because you can no longer downplay expectations & get away with it. When you sign Ronaldo, standards/expectations MUST rise.While it has been great for him, it has only mounted more pressure on Manchester United to perform accordingly. The Red Devils have suffered from changes in management and players on multiple occasions before Ronaldo arrived this summer.They are a team with potential but still in a growing process. To add, the Premier League is a very different league compared to the other leagues he has played in the last decade. Hence, it is very difficult to meet these expectations so quickly.#4 Lack of link-up with wide playersManchester United v Aston Villa - Premier LeagueOne of Manchester United's signature moves is to involve their wide players into the game. May it be the full-backs or the wingers, the Premier League giants like to use the width under Ole Gunnar Solskjaer to its fullest.Mason Greenwood was one of Manchester United's best players earlier this season, playing on the right wing. Unfortunately, him and Cristiano Ronaldo have not been able to link up that well. Jadon Sancho, Marcus Rashford and other wide players have struggled to find Ronaldo on a regular basis as well.ESPN UK@ESPNUKSolskjaer is struggling to get Ronaldo and Greenwood to link up, sources have told @MarkOgden_ 😬6:37 PM · Oct 25, 20213824265Solskjaer is struggling to get Ronaldo and Greenwood to link up, sources have told @MarkOgden_ 😬 https://t.co/LxG7XfIzDpThere is a cohesion that's been lacking between the wide players and the Portuguese captain. Given how heavily Manchester United rely on their wide players, the lack of sync between them and Ronaldo is one of the reasons why they have struggled.