Roman Abramovich's Chelsea have been the epitome of defensively sound and imperious football over the last two decades.Chelsea have been known for their fortitude, right from the reign of Jose Mourinho. Under the Portuguese boss, John Terry and Ricardo Carvalho led Chelsea to back-to-back Premier League crowns. The likes of Gary Cahill and David Luiz, followed by present day defenders Thiago Silva and Cesar Azpilicueta have all helped Chelsea keep a defensive shine.Despite the many great defenders in the club's history, Chelsea have also had their share of unreliable stoppers that worked against expectations. Here's looking at 5 of Chelsea's most disappointing defenders in the Roman Abramovich era:#5 Tal Ben HaimMaccabi Tel-Aviv FC v Chelsea FC - UEFA Champions LeagueTal Ben Haim was signed in June 2007 as an imposing no nonsense centreback from Bolton Wanderers. Chelsea swooped in for the Israeli centreback on what looked to be an astute signing, providing cover to the likes of John Terry, Gallas and Carvalho.Very quickly, however, he found himself at the tail end of the pecking order, with subpar performances putting Brazilian Alex above as a starter. It soon all came to a bitter end as he vocally criticized manager Avram Grant for not playing him. He was fined two weeks' wages for public dissent, insisting that he signed up to play for Jose Mourinho.MailOnline Sport@MailSportDidier Drogba wanted to 'KILL' Tal Ben Haim, Essien 'snapped' Shevchenko... and Jose 'thrived off' it! Steve Sidwell lifts the lid on the culture Mourinho created at Chelsea trib.al/UN0p3jZ2:45 AM · Feb 5, 2021323Didier Drogba wanted to 'KILL' Tal Ben Haim, Essien 'snapped' Shevchenko... and Jose 'thrived off' it! Steve Sidwell lifts the lid on the culture Mourinho created at Chelsea trib.al/UN0p3jZHe was never to play for the club again as Chelsea packed him away to Manchester City. The Blues made a healthy 5 million pound profit from the transfer. Having once again failed to establish himself in the first team, he went out on loan to Sunderland. He then proceeded to have a journeyman career at the likes of Portsmouth, West Ham, Queen's Park Rangers, Standard Leige and Charlton Athletic. He finally returned "home" to Maccabi Tel Aviv.#4 Yuri ZhirkovChelsea v Watford - FA Cup 3rd RoundYuri Zhirkov arrived at Chelsea in 2009 from CSKA Moscow as the most expensive Russian player in history, having made the Euro 2008 team of the tournament. The near £18 million fee for Zhirkov was exuberant, despite his versatile ability to play anywhere on the left flank. He was primarily seen as a hardworking and industrious full-back.Despite his obvious ability, Zhirkov found it hard to displace Ashley Cole from the starting spot. He was instead reduced to a utility-man role for two seasons until 2011, when the riches of Anzhi Makhachkala came calling.UEFA EURO 2024@EURO2024🇷🇺 Happy birthday, Yuri Zhirkov 🥳🔝 Who's your favourite player to represent Russia? #HBD | @TeamRussia4:29 AM · Aug 20, 202132327🇷🇺 Happy birthday, Yuri Zhirkov 🥳🔝 Who's your favourite player to represent Russia? #HBD | @TeamRussia https://t.co/InP2euFBI0Despite his failure at Chelsea, Zhirkov is recognized as one of the greatest Russian players of all time. He played in five international tournaments and earning 105 national caps. Zhirkov has a storied playing career with Dynamo Moscow and Zenit St. Petersburg after his Anzhi expedition.