Since Roman Abramovich became Chelsea owner 18 years ago, the Blues have tasted success in abundance. They have not been afraid to take a short term approach to success and that has yielded results for them in various ways. Under the Russian's reign, Chelsea haven't been shy about showing the door to their managers.With all those managerial changes came new philosophies and strategies to steer the ship at Chelsea, which weren't to the liking of many players. Some fell out with their gaffers, some simply did not fit into the system. There were also instances when the managers ran out of patience with certain players.Chelsea have one of the most expensive squads in EuropeUnder Thomas Tuchel, Chelsea are the Champions of Europe and one would feel they have one of the strongest squads on the continent. But nothing is ever too perfect. There are players that Chelsea have let go of and in hindsight. there are some exceptional ones about whom the Blues management might have second thoughts now.So we decided to rub a little salt on those wounds, if we may say so by presenting the most valuable XI let go by Chelsea as of October 2021:GK - Thibaut Courtois (€60m)Tottenham Hotspur v Chelsea - Premier LeagueThe lanky Belgian served at Chelsea from 2014 to 2018, after returning from a three-year loan spell at Atletico Madrid that consisted of two 12-month extensions. Thibaut Courtois won the Premier League on his return in 2014-15 under Jose Mourinho's reign and then in 2017 with Antonio Conte at the helm.Last season, he went up against Chelsea in a Real Madrid shirt for the first time since leaving. Over the course of two ties, Courtois conceded three goals to the Blues as Los Blancos bowed out of the Champions League with the scoreline reading 3-1 on aggregate.Sky Sports News@SkySportsNews🗣️ "They don't care about the players they just care about their pockets." Thibaut Courtois accused UEFA and FIFA of prioritising money over player welfare after Belgium were beaten 2-1 by Italy in the Nations League third-place play-off.12:35 PM · Oct 11, 2021243403941🗣️ "They don't care about the players they just care about their pockets." Thibaut Courtois accused UEFA and FIFA of prioritising money over player welfare after Belgium were beaten 2-1 by Italy in the Nations League third-place play-off. https://t.co/0RbBu0Ux6hCourtois always desired to move to Madrid and Los Blancos were his dream side. In his second season with Real, he helped them to the La Liga title by conceding just 19 goals in 34 games he played.2018 was the best year for the former Chelsea goalkeeper, who contributed massively as Belgium achieved their personal best third position in a World Cup. He won the Golden Glove in Russia, which also helped him win the FIFA Best goalkeeper award.LB - Nathan Ake (€32m)Netherlands v Estonia - UEFA Euro 2020 QualifierNathan Ake joined Chelsea at a young age of 15 and made his Premier League debut at 17 in 2012. Since emerging at Chelsea, Ake has established his image as a utility player in the backline. He prefers a centre-back role, but has frequently been deputized at left-back and sometimes even as a central defensive midfielder.The early signs were positive and after winning Chelsea's young player of the year award in 2013, the Dutchman must have thought he would settle into the side well. The Blues wanted to give Ake all the time to develop and loan moves to Reading, Watford and Bournemouth followed before he transferred permanently to the latter.The former Chelsea man was always praised for his work ethic and his sincerity. Currently employed at Manchester City, Ake is not the first name on the starting sheet. However, he does get decent game time from the bench and remains an integral squad player.CB - Fikayo Tomori (€40m)Tomori has no regrets of leaving ChelseaIt is difficult to understand why Chelsea let go of Fikayo Tomori without really putting up a fight but eventually it seems like a win-win for all parties. The Chelsea graduate was the subject of three loan moves to the Championship after making his debut in 2016.He returned to first-team action in 2019 with the Blues and soon opened his account with an unlikely long-range curler against Wolves. With Frank Lampard's arrival, there was some promise of breaking into the first team for Tomori but the chances were limited.Omar Elbamby@Omar_BambySpectacular clean tackle as usual from Fikayo Tomori❤️1:54 AM · Oct 17, 202151Spectacular clean tackle as usual from Fikayo Tomori❤️ https://t.co/WgwCONHUDVAfter Tuchel's arrival, Tomori was loaned to AC Milan in January 2021 with an option to buy. Little did the 23-year old know he'd be the heartbeat of Milan's defense and finally get to settle for good. Tomori's explosive pace and aggressive defending have impressed Milan director Paolo Maldini and former Milan boss Fabio Capello. The Rossoneri triggered the option to make his move permanent earlier this summer.CB - Kurt Zouma (€32m)David Moyes is a big admirer of Zouma's abilitiesKurt Zouma ended his seven-and-a-half-year-long association with Chelsea in the summer transfer window after joining high-flying West Ham United. Zouma scored on his Chelsea debut in 2014 and throughout his time at the club remained a threat to the opposition in set-piece situations.During his time at Chelsea, Zouma won the Premier League title twice in 2015 and then in 2017. In his first season with Chelsea he was named the young player of the season. The France international managed a handsome tally of 151 appearances for Chelsea and netted 10 goals.PurelyFootball®️@PurelyFootballKurt Zouma on Mourinho: “We were losing 3-1, away. The following day, he catches up with me, takes me to his office, and asks me if I am ok. I said yes, he asked me if I was sure. I said yes again, he replied: 'Because you were rubbish this weekend.”Classic Jose.7:56 AM · Oct 16, 20212908273Kurt Zouma on Mourinho: “We were losing 3-1, away. The following day, he catches up with me, takes me to his office, and asks me if I am ok. I said yes, he asked me if I was sure. I said yes again, he replied: 'Because you were rubbish this weekend.”Classic Jose. https://t.co/RxzFAmyP0GHe has made four appearances for West Ham so far and it is quite evident that Zouma is more suited to a back four system than Tuchel's back-three at Chelsea. He will hope that he gets regular game time so the 26-year old can break into the France starting XI on a regular basis.RB - Juan Cuadrado (€16m)Cuadrado scored in Juventus' opener against UdineseJuan Cuadrado has had to redefine his playing style in order to stay relevant to changing times at Juventus. He has predominantly started in the right-back position in the last few years and has been excellent. It is quite commendable since he eventually started off as a winger.At 33, he's still meeting the intense demands of the game in Serie A and is one of the few positives in an otherwise weakening Juventus squad. Cuadrado was signed by Chelsea in 2015 following his impressive showing at the 2014 World Cup. This was a player plus cash deal and the player going the other way was, wait for it...Mohamed Salah!In Tuchel's 3-4-3 system today that thrives on adventurous wing-backs, Cuadrado would have been quite successful with his directness and his ability to go up and down the flanks. The Colombian only made a mere 15 appearances for Chelsea and his only goal contribution was an assist in a Premier League game.