Chelsea arguably had one of their best transfer windows this summer as the club managed to fill the gaps in their squad while also offloading a lot of deadwood.While the club missed out on Jules Kounde, they managed to sign a much-needed striker in the form of Romelu Lukaku for £97.5 million. They also signed midfielder Saul Niguez on deadline day of the transfer window.Chelsea also let 28 players depart Stamford Bridge this summer. 10 of these players departed permanently this summer, with the rest going out on loan. The most notable sales were that of Tammy Abraham and Fikayo Tomori, who have both been sold to Serie A, while Kurt Zouma moved to London rivals West Ham.A few Chelsea loanees have no future at the clubChelsea's loan system is no secret. The Blues have plenty of players out on loan each season. While most are young players who are sent out to gain some experience, others are just failed transfers who did not perform up to the mark.These players did not impress enough during their time with the first team and it's better if they never play for the club. So here we take a look at five such players who should never play for Chelsea again:#5 Matt MiazgaMiazga failed to fulfill his potential at ChelseaMany eyebrows were raised when Chelsea signed young American centre-back Matt Miazga from the New York Red Bulls in 2016. The then 20-year-old never looked like someone who could play regularly for Chelsea and that's exactly what happened.Miazga was afforded just two Premier League outings in his debut campaign but has not played a competitive game for Chelsea since. He eventually ended up in the Chelsea loan army and has had temporary spells with Vitesse Arnhem, Nantes, Reading and Anderlecht, racking up 156 appearances away from Stamford Bridge.The American spent last season at Anderlecht and the Belgian giants were reportedly ready to extend Miazga's stay at the club. However, since he proved not feasible, they moved onto other targets, leaving Miazga to return to Chelsea.Miazga extended his contract by one-year till 2023 and was immediately sent on loan to La Liga side Alaves for the 2021-22 season.American defender Matt Miazga joined Alaves today on a loan deal. Since joining Chelsea in 2016 and making two appearances: 🇳🇱 Vitesse (Loan: 2016-18)🇫🇷 Nantes (Loan: 2018-19)🏴󠁧󠁢󠁥󠁮󠁧󠁿 Reading (Loan: 2019-20)🇧🇪 Anderlecht (Loan: 2020-21)🇪🇸 Alaves (Loan: 2021-) pic.twitter.com/BwuvnaXjHL— B/R Football (@brfootball) August 20, 2021With Miazga failing to create a big impression on loan and Chelsea already boasting quality centre-backs in the squad, he might never don a Chelsea shirt again.#4 Baba RahmanBaba's time at the club was marred with injuriesOne of the signings in which Chelsea have suffered the most financial loss is Abdul Baba Rahman. Bought from Augsburg in the 2015-16 season for £23.4 million, the full-back could not even return a fraction of that worth as a player due to his recurring injuries.After signing a five-year deal with Chelsea, Rahman spent the 2015-16 campaign with the Blues, making 15 Premier League appearances for the side.But his limited game time due to injuries forced him out on loan to Schalke the following season. That was followed by subsequent loan spells at Stade Reims, Real Mallorca and most recently at Greek club PAOK, where he spent the second half of last season.Now 27, Rahman was expected to be sold by Chelsea. But surprisingly he was given a new contract and sent out on loan to Reading in the Championship.🚨 Abdul Rahman Baba, 27, on loan until the end of the season to Reading from Chelsea.The athlete joined the "Blues" in 2015 for 26 million euros and has since been loaned six times. pic.twitter.com/95xZmRSSt0— World of Football (@Infogenuino) August 27, 2021The left-back's recurring injuries have shown that he is not a viable option for Chelsea. The club can only hope that he does well in the Championship so that they can sell him for some extra money soon.