These six were meant to become future legends, however unfortunately for them, it didn't pan out that way.
Even despite putting in hours of preparation, weeks - or even months - of scouting, and doing everything you can to make sure a new signing fits in well, sometimes it just doesn't come off.
For Manchester United, this seems to have been a more regular occurrence in the last few years, with players tipped for greatness, only to crumble, or just not deliver. Here are six players the Red Devils signed that never hit the targets hoped for them.
Nick Powell (L) scores the fourth goal for Manchester United
Dubbed 'the new Steven Gerrard', hopes were high for Powell, who arrived at Old Trafford in 2012 aged 18 on the back of an excellent season with League 2 side Crewe Alexandra, which culminated in Powell scoring an outstanding volley at Wembley Stadium to help Crewe win the play-off final 2-0. Things got off to an outstanding start, with Powell scoring on his debut in a 4-0 win over Wigan Athletic, however things went downhill from there. Loan spells at Wigan Athletic, Leicester City and Hull City showed that perhaps Powell isn't quite 'United good', and he was released in the summer of 2016. Powell is now back at Wigan, where he has scored one goal in 15 games this season.
It's maybe a bit harsh to say someone who won four Premier League titles, a Champions League, the Club World Cup and two League Cup winners medals flopped at United, but had Anderson lived up to his potential, he'd still be at the club now. After arriving from Porto in 2007, Anderson initially started brightly for United, but his debut season would be the only one where he played more than 20 Premier League matches, as it became apparent he wasn't at the ability required. Anderson left United in 2015 to head back to Brazil with Internacional, though he is currently on loan at Cortiba.
Manchester United's Memphis Depay in action with Fenerbahce's Alper Potuk
Then 21-year-old Depay signed for United in 2015 having torn apart the Eredivise with PSV Eindhoven, who'd just won the league with Depay as top scorer, and the winger was described as the best young talent to emerge from the Dutch top flight since Arjen Robben. However, Louis van Gaal's style of management crippled anyone with any attacking threat, and the Holland international was soon made to look like a flop. After eight appearances this season, Jose Mourinho sold him to Olympique Lyon in the January transfer window, where he's scored five goals in nine matches so far. This may have a happy ending however, as United inserted a buy back clause, as reports the Manchester Evening News.
The United academy graduate, who was poached from SS Lazio in 2007, was destined for greatness after scoring a staggeringly brilliant goal at the death to snatch a 3-2 win for the Red Devils against Aston Villa, with Macheda doing a Cruyff turn of sorts in the box to get away from his marker, before firing into the top corner. Greatness never came however, and Macheda was loaned out to Sampdoria, Queens Park Rangers, VfB Stuttgart, Doncaster Rovers - twice - and Birmingham City, before signing for Cardiff City in 2014 following his release from United. Macheda is now at Italian side Novara.
Manchester United's Chris Smalling, Wayne Rooney, Phil Jones and Radamel Falcao celebrate at full time
You have to feel a bit sorry for 'El Tigre' here, as his loan spell at United from AS Monaco was meant to lead to a permanent transfer and a return to form after a serious injury which left Falcao missing the 2014 World Cup with Colombia. It wasn't to be however, as Falcao also fell victim to van Gaal's suffocating style of play for attackers. and scored just four league goals in 26 matches - 12 of which came from the bench. A loan spell at Chelsea after his disappointing stint at Old Trafford followed, again with Falcao being deployed from the bench, before he returned to Monaco this season. Any lingering doubts over his ability have been extinguished, with the Colombia international scoring 21 in 28 this season, including a brace against Manchester City in the Champions League.
Angel Di Maria
The biggest victim of all from the van Gaal era, and one that United could regret most should they get back to mixing it up with Europe's elite. Having signed for a then record fee of £59.7m, as reports the club's official website, the winger - who arrived from Real Madrid having just won the Champions League there - showed glimpses of his quality, but was never played correctly enough to show it properly. After a year of frustration from both the player and supporters, he was sold to Paris Saint-Germain, and has since showed just why he's still one of Europe's best wingers, to the point Mourinho said recently that he wouldn't have sold him, as reports the Telegraph.