#4 Yerry Mina (Barcelona to Everton)
Looking at the World Cup, Mina looked like a decent player. He scored three goals for Colombia in Russia, the most by any defender at the tournament. £30 million is a lot of money to pay for a player who has played just five league games in Europe since his £10 million move to Barcelona in January though. He started four of those, and one of them was the 5-4 defeat to Levante.
Mina did have a decent World Cup with Colombia, but defensively he sometimes looked a little bit unsure, and although he was a threat in the opposition box, he had some difficulties in his own. Everton needed to invest in a centre back this summer after some shocking defensive displays last season, and both Ramiro Funes Mori and Ashley Williams leaving Goodison Park. Mina may not be the answer though, so it will be interesting to see how he gets on.