Last summer Kalidou Koulibaly arrived at Chelsea when it felt like the club were in dire need of a defender. The Senegal international arrived at a time when Chelsea were reeling from the departures of Antonio Rudiger and Andreas Christensen on free transfers with Trevoh Chalobah, Malang Sarr and Thiago Silva making up Thomas Tuchel's options in the centre of defence in addition to returning loanees Levi Colwill and Ethan Ampadu.
In many ways his £33 million arrival looked like it could be good business, though there were perhaps some concerns around the longevity of the move given Koulibaly's age. He offered a show of promise in a disappointing pre-season defeat to Arsenal, and produced an early moment of magic with his goal against Tottenham.
The 32-year-old's performance in the next game against Leeds United is perhaps what cemented many people's opions of Koulibaly's abilities in the Premier League, however. Two yellow cards and a consistent difficulty to retain any pace on the turn overshadowed any positive aspects that followed over the course of the season, with the defender's days at Chelsea looking even more under threat when Benoit Badiashile arrived in January.
However, the Frenchman's move to the club left many concerned over the future of Colwill. While the Blues retained hopes of extending Colwill's deal, the arrival of a young, left-sided central defender for in excess of £30 million left many drawing comparisons between the two.
The Cobham product enjoyed a positive season at Brighton after starting the season on the bench when he moved to the south coast as Marc Cucurella made the move to Stamford Bridge. Colwill spent time in first team training, even being used in the heart of a back-three at times, but saw his training disrupted by injury, with a move to the Seagulls completed while Thomas Tuchel was hesitant with the information he had to work from.
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While Colwill's lack of Premier League experience could have been cited as a reason to not trust him with a starting position in Chelsea's defence 12 months ago. That is no longer the case after the 20-year-old helped Brighton to European football.
Colwill is currently participating in the under-21 European Championships and has helped England to two clean sheets in their opening two games, and also spent time with the senior side earlier in the month. He may not be ready to go for Mauricio Pochettino's first day of pre-season due to his involvment but his intention will be to break into the side, and the Blues must convince him he has a role to play.
Chelsea seem likely to move to a back four under Pochettino with Colwill, Badiashile, Chalobah, Silva and Wesley Fofana all competing for two spots. That looked more unworkable with Koulibaly still in the building and the defender's departure will signal to those remaining that they are deemed a greater priority, with a pathway for Colwill becoming more obvious.
The young defender has been declared not for sale while Badiashile is recovering from injury. Chalobah had held a meeting over a move to Inter Milan, while Silva is once again in the final year of his contract.
The deal is a positive step toward cutting down bloated squad numbers while also being able to concretely show to talents such as Colwill that they will be provided with an opportunity in the coming season. It will certainly allow the club to put forward a more convincing argument to ensure Colwill signs a contract extension.
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