3. Romelu Lukaku (£75m – Everton to Manchester United – 2017) Flop
Lukaku, another United acquisition that fell short of expectations, signed with the club the day after Wayne Rooney made his way back to Everton. Lukaku got off to a fast start for the club, scoring 10 goals in his first nine games.
He eventually finished the season with an impressive 27 goals in 51 games. But he would have a considerably tougher challenge during his second campaign at Old Trafford.
After going 12 games without scoring, Lukaku came under intense scrutiny. Ole Gunnar Solskjaer, who took over for Jose Mourinho, later dropped the Belgian international.
Lukaku scored 15 goals in all competitions as the season came to a close, however he transferred to Inter Milan that summer after United was able to recover the entirety of the £75 million transfer cost they had given to Everton in 2017.