Opinion: Manchester United have finally got their act together but still need to strengthen three areas

Manchester United finally seem to have got their act together in the transfer window.

After a number of largely frustrating summers, the club seem to be eventually addressing problems in their squad that date back to the final years of Alex Ferguson's reign. United have needed a dominant central midfield player for years, they've signed two this week. For many, Bastian Schweinsteiger fills a void that Roy Keane left when he departed Old Trafford almost ten years ago. In term's of personality, playing pedigree and stature within the game, Schweinsteiger is the closest United will ever get to Keane. The 31-year-old is entering the autumn of his career, and has struggled with injuries the past 18 months, but still possesses the ability and professionalism to slot straight into Louis van Gaal's team. It's United's other midfield signing that is arguably the more exciting for the club's fans. Morgan Schneiderlin is an excellent player, and would improve any squad in the Premier League. The 25-year-old is the near complete midfielder, adept at reading the game and tackling and very comfortable in possession. While United never replaced Keane, they now have a ready-made replacement for Michael Carrick, and a much needed physical presence in central midfield. The team's purple patch towards the end of last season was ended at Stamford Bridge, where Chelsea ground out a 1-0 win. United were noticeably poorer for Carrick's absense, but they also lost the physical battle. Ander Herrerra was deployed in a deeper position than in previous games, and had started the game brightly. Until he got some rough treatment by both Didier Drogba and John Terry, before Chelsea's first-half goal, then arguably disappeared for the rest of the game. Schneiderlin certainly won't be bullied, and is capable of dictating play like Carrick. In addition to Schweinsteiger and Schneiderlin, United have also signed Matteo Darmian, seemingly solving another problem position. The Italian international is versatile, but will play at right-back, where makeshift defender Antonio Valencia predominately played last season. Ferguson favourite Rafael appears to be in his final days at Old Trafford. Unless you regularly watch Serie A, you may not be too familiar with Darmian. You may remember him from the World Cup last summer, where he was excellent against England and a bright note for the Azzuri in an otherwise disappointing tournament. The former Torino defender is athletic, comfortable in possession and offers both an attacking threat, and security at the back. So that's what United have added so far, but holes remain in their squad, and uncertainty over their best player. Here's the other areas of Van Gaal's squad that need strengthening, and some options that may be worth exploring. Striker With Robin van Persie gone, Javier Hernandez injured, and seemingly not in the manager's plans anyway, United only have Wayne Rooney and James Wilson as first-team strikers. Of Rooney's 33 Premier League games last season, just 14 were at centre-forward. The United captain's versatility could be the reason for this, but, with Radamel Falcao and Van Persie either injured or out of form, it was puzzling that Van Gaal didn't use Rooney more often as the team's central striker. This could mean the United manager doesn't see Rooney's future at centre-forward, or that needs dictated playing him elsewhere. Either way, United need a new striker, and the potential signings mooted so far look like calculated gambles at best. Edinson Cavani is the latest high-profile striker to be linked with a move to Old Trafford, as part of a potential swap deal with Angel di Maria. The Uruguayan has struggled in Zlatan Ibrahimovic's shadow at PSG, but has a good strike rate when played at centre-forward, scoring 12 goals in 23 Ligue 1 games when played up front last season. He's also an athletic, industrious player and often prepared to sacrifice his natural game to aid his side, whether it's for Zlatan at PSG, or Luis Suarez at international level. Van Gaal would appreciate such qualities, however there'd be an awful lot of uncertainty around this move, should it happen. A swap deal, plus transfer fee, for Di Maria would be highly complicated, and unlikely to be completed by the time the Premier League season kicks off on August 8. While Cavani has often underperformed in big games when played as the central striker. He missed a clear chance against Chelsea in the Champions League last-16 tie last season, and was poor against Costa Rica in Suarez's absence in the World Cup last year. There's also a big risk that the player won't settle in Manchester, with recent South American imports, such as Di Maria and Falcao struggling to adapt. If United were to sign Cavani, they'd be getting a player in his peak, but would the 28-year-old be a worthwhile risk? A safer option might be Liverpool target Christian Benteke. The Aston Villa striker is proven in the Premier League, and was excellent in the later half of last season. The Belgian striker scored 13 goals in 26 games, and went on a fantastic run of form to help keep his side in the Premier League. Benteke is just 24, and would arguably be a better fit in United's squad. He'd cost less, in terms of wages and transfer fee, than Cavani, and wouldn't be an automatic first choice starter, therefore, Rooney's nose would not be put out of joint. However, the options remain slim for United. Ed Woodward may covet a high-profile signing, like Cavani, but there's considerable risk, and paucity of options, for such a deal. A younger, less internationally established, but proven Premier League player like Benteke may be the better option. Central defender With Jonny Evans reportedly not in Van Gaal's plans, and Phil Jones and Marcos Rojo failing to fully convince last season, United need to strengthen in central defence. Mats Hummels appeared certain to join United, only for the Borussia Dortmund defender to commit his immediate future to the German club. Sergio Ramos reportedly told Real Madrid he wants to leave, and only join United, but he's currently on his way to the club's pre-season tour, and was named new club captain. It's possible that Ramos' move to Old Trafford could still materialise, and may hinge on David de Gea's future. However, United need to cover themselves, and be wary that they're not just been used as a means to earn the player a more lucrative contract at the Bernabeu. Either Valencia's Nicolas Otamendi, or Everton's John Stones, could be options for United. Otamendi was excellent for Valencia last season, and has all the necessary qualities to thrive in the Premier League. The Argentine is aggressive, reads the game well and is strong in the air and in challenges. While not quite as comfortable in possession, or as technically gifted as Ramos, the 27-year-old would a very good signing for United. He also offers a goal threat, having scored six goals for Valencia last season. If both Ramos and Otamendi's transfers fail to materialise, a move for Stones would be worth exploring. The 21-year-old has shown plenty of promise so far at Everton, and is exactly the type of player Van Gaal works best with: a young, talented, player, who's both comfortable in possession and possesses all the physical capabilities to develop in a top class player. Stones looks set to eventually move to a Champions League team. United would be wise to move before Manchester City or Chelsea come calling for the youngster. Goalkeeper United are going to have to replace De Gea eventually. Whether he joins Real Madrid this season, or United force him to see out the remaining year of his contract, the Spanish goalkeeper isn't long for Old Trafford. De Gea has been United's best player in the post-Ferguson era, and will be a tough act to follow, but the club appear to have their eye on a number of potential replacements. Hugo Lloris is the pick of the bunch. The Spurs and France captain is lightning quick off his line, allowing his team to play a higher defensive line, and is comfortable using his feet. He's also very athletic and agile, and a proficient shot stopper. United have had trouble dealing with Spurs' club chairman Daniel Levy in the past, so a deal for Lloris wouldn't be cheap, or smooth, but he'd be a capable replacement for De Gea. United would have to wait until the player overcomes a fractured wrist, if they were to sign him, but it'd be worth the wait. Jasper Cillessen has also been linked to United. The Ajax goalkeeper worked under Van Gaal with the Dutch national team, (he was substituted for Tim Krul before the Netherlands' penalty shoot-out against Costa Rica in the World Cup quarter-finals), and is the archetypal "sweeper 'keeper". The 26-year-old is as proficient with his feet as he is saving shots, an aspect Van Gaal would look for in the next United number one. However, Cillessen would arguably be vulnerable under crosses, and has a tendency to try punch the ball, rather than catch it. If he were to join United, a difficult settling in period could await, and United's defence wasn't exactly water-tight last season. De Gea was arguably the difference between the side gaining Champions League football and missing out for another season. Back-up goalkeeper Victor Valdes has been left out of United's pre-season tour of the United States, suggesting Van Gaal doesn't see him as a adequate replacement for De Gea. United appear to have had a very good transfer window thus far. They strengthened some problem positions, and have cut loose expensive, 'dead wood' in the form of Van Persie and Nani. However, the club are potentially  two or three signings away from a great transfer window, and a possible title challenge.