As Manchester United splashed out £150m on Marcos Rojo, Luke Shaw, Daley Blind, Ander Herrera, Angel Di Maria and Radamel Falcao, some players had to leave. Recent deals saw Tom Cleverley, Tom Lawrence and Nani leave the club on loan or permanently.
Yet one of the biggest exits saw playmaker Shinji Kagawa depart Old Trafford in order to return to former club Borussia Dortmund just two years after initially leaving Signal Iduna Park. The Japanese arrived in Germany from Cerezo Osaka back in 2010, and impressed massively with 29 goals in 71 games from midfield.
Suitably impressed with his performances in the Bundesliga, Sir Alex Ferguson forked out around £17m to bring him to the Premier League - despite the limited success of his compatriots Junichi Inamoto, Ryo Miyaichi and Kazayuki Toda in recent years.
However, Kagawa's time at Old Trafford was plagued by loss of form and fitness, and he scored just six goals in 57 games for United - and three of those goals came in one game against Norwich City.
With new United boss Louis van Gaal unhappy at Kagawa's inability to adapt his game to playing in a deep role, it was little surprise to see him sold just days before the deadline, as Kagawa rejoined Dortmund for a cut-price £6m deal - and Arsenal defender Per Mertesacker says Kagawa will be better back in the Bundesliga than he was at United.
"At Manchester United, it was not easy for him to find his rhythm which he had in Dortmund," says Mertesacker. "He made only 38 Premier League appearances. Germany has him in a better location, for him it is now easier again with his new, or rather old, team coach Jurgen Klopp. Despite the two years in England, his quality did not diminish."
Reunited with manager Klopp, it would be little surprise to see Kagawa recapture his best form now he's back with Dortmund. Alongside Marco Reus, Henrikh Mkhitaryan and Ciro Immobile, Dortmund could have quite the attack on their hands - even having lost Mario Gotze and Robert Lewandowski in successive summers.