#4 Mousa Dembele instead of Marouane Fellaini

David Moyes signing Maouane Fellaini when he came to United as perhaps the most predictable transfer of the year. Fellaini had performed well at Everton, used as either a box-to-box midfielder by Moyes or a physical presence up front, Fellaini was effective and had shown his worth against United several times, most notably the opening day of the 2012/13 Premier League season at Goodison Park.
Fellaini's first season at United was a near disaster, with Moyes seemingly reluctant to use him as he did at Everton, and instead opting to play Fellaini as a defensive midfielder, and it was unsurprising when many United fans demanded he was sold as soon as Moyes left.
He's proved his worth since, particularly under Jose Mourinho, who seems to know how to get the best out of Fellaini amongst this current United squad.
In 2013, Fellaini was not what United needed, this was clear, energy and composure in centre midfield was, and Mousa Dembele would have been a much better option. Linked with United for just £10 million the summer before, Dembele would have been a bargain for what United would have gotten.
Often a regular for Spurs, Dembele is comfortable both in front of the back four and getting forward to join the attack. He has the composure and technique on the ball and is often seen driving forward with the ball from deep, traits that were missing in United's midfield. Many of Dembele's trademark characteristics are exactly what Fellaini lacks.