When Manchester United signed Jadon Sancho, Raphael Varane and Cristiano Ronaldo last summer, they were immediately viewed as title contenders. It didn't take much time for all that initial hype to fizzle away and the way things are going, the Red Devils might not even qualify for the Champions League next season.Raphael Varane has done well in defence. Jadon Sancho has been one of Manchester United's best players since the turn of the year. Cristiano Ronaldo did well initially but has seemed lost in recent weeks.Manchester United are set for a hectic summer transfer windowInterim manager Ralf Rangnick has confirmed that signing a young striker is now a priority for Manchester United in the summer transfer window. It is clear now that the Red Devils need to bolster a few other departments as well.This summer's transfer window is going to be an exciting one, with plenty of high-profile stars set to become free agents. Here, we take a look at five free agent signings that can absolutely transform this Manchester United side.#5 Boubacar Kamara (Marseille)Bouacar Kamara in action for Marseille (pic cred: Alley Sport)Boubacar Kamara is one of the most exciting midfield prospects to emerge from France in recent times and that is saying something. The Marseille academy graduate was linked with the Red Devils in January but a move didn't materialize.The 22-year-old is the kind of well-rounded midfielder that Manchester United should look to sign in the summer. He is a tenacious presence in the middle of the park and excels at making blocks, interceptions and recoveries. Kamara is a ball-winning midfielder who is also adept at retaining possession.He is press-resistant, is an excellent dribbler and has the technical finesse to link-up with teammates even in tight spaces. Kamara's long balls are also pretty accurate and he would be a great long-term signing for the Old Trafford outfit.He made his senior debut for Marseille a little more than five years ago and already has plenty of experience playing in Europe as well.Get French Football News@GFFNMarseille have won just 3 of their last 23 matches when Boubacar Kamara (22) isn't playing for them - via @Statsdufoot.His situation, leaving for free in summer, represents serious mismanagement from Pablo Longoria, who fell out badly with the player & failed to resolve.3:44 AM · Feb 10, 20227815Marseille have won just 3 of their last 23 matches when Boubacar Kamara (22) isn't playing for them - via @Statsdufoot.His situation, leaving for free in summer, represents serious mismanagement from Pablo Longoria, who fell out badly with the player & failed to resolve.#4 Ousmane Dembele (Barcelona)FC Barcelona v Club Atletico de Madrid - La Liga SantanderOusmane Dembele has been heavily linked with Manchester United in the past. The Barcelona winger's current contract expires in the summer and the Catalans have confirmed they won't renew his contract.When he is fit and playing, Dembele is a world-class winger. But his persistent injury problems could be a real pain in the neck for Manchester United, who are currently without an out-and-out right winger.The 24-year-old has scored 31 goals and provided 23 assists in 129 appearances across all competitions for the Catalans since joining in 2017. He could be worth the gamble for Manchester United. They will need to pay him a hefty sum in wages, which was the bone of contention between him continuing at Barcelona in the first placeBut if they can keep him fit and disciplined, they will have landed themselves a world-class winger.mufcmpb@mufcMPBManchester United are negotiating with Ousmane Dembélé’s agent, Moussa Sissoko, for a summer move. Barcelona ‘know first-hand’ his agent has been meeting with United in recent weeks. Figures have been discussed and they would match Juventus. #MUFC [@sport via @Sport_Witness]9:48 AM · Feb 7, 2022160795Manchester United are negotiating with Ousmane Dembélé’s agent, Moussa Sissoko, for a summer move. Barcelona ‘know first-hand’ his agent has been meeting with United in recent weeks. Figures have been discussed and they would match Juventus. #MUFC [@sport via @Sport_Witness]