Failure to win the Premier League
Liverpool made a serious challenge for the title in 2008-09 and it appeared as though they had matured from annual pretenders to realistic contenders for the coveted crown back in August.
When the former Valencia boss took over the helm vacated by Gerard Houllier in June 2004, the main part of his job description was clear: bring much-craved championship success and glory days back to Merseyside.
Despite the famous Champions League victory of 2005, and FA Cup success the following year, Benitez's trophy haul was not up to the heady standards set in eras gone by.
The much-heralded dominance on all fronts of the great Liverpool sides of the 1970s and 1980s has left many in the Kop with a feeling of superiority and dreaming of better times. With no title success in 20 barren years, and no sign of any immediate change in these fortunes, the natives became restless.
In Benitez's defence, his time in the Anfield hotseat was littered by boardroom unrest and constant media speculation of rifts between the manager and American owners George Gillett and Tom Hicks.
The ambitious Gillett/Hicks partnership took control in early 2007 with big promises and an apparent mountain of cash to spend on the team.
Amidst stories of fall-outs between the pair, and rumblings of money shortages that left Benitez's transfer kitty severely reduced, the manager was severely hampered in his pursuit of glory for the club.
Haunted by the past
The Spaniard has had his detractors since making the move to England, and draws constant unavoidable comparisons to the leaders of previous glorious Liverpool sides, including legends Bill Shankly and Bob Paisley.
With the added pressure of title-winning boss Kenny Dalglish hanging around in the Anfield shadows as club ambassador, and frequent calls for the Scot to return to the manager's role, Benitez had to constantly deal with the ghosts of the past and memories of the expectations he ultimately failed to meet.
With the added media analysis and opinion from ex-players into each and every decision he made, it showed the stringent belief the 49-year-old had in his unique methods - not to mention a strength of character - to stick to them.
Throughout his time as boss, Benitez was time and time again criticised for his unpredictable and sometimes puzzling team selections and dependency on a squad rotation policy.
Although it can be argued that such systems have been deployed successfully at Manchester United and Chelsea in particular, Liverpool's over-reliance on star players Steven Gerrard and Fernando Torres and lack of squad depth was widely condemned.
At times it seemed that when his match-winning duo were injured or not on top form, Benitez's sides were devoid of creativity and showed a distinct lack of the guile and quality needed to break teams down.
Benitez had a mixed record in the transfer market in his time at Anfield.
The most expensive flop appeared to be the ill-fated signing of Robbie Keane from Tottenham for £19million, as without gaining a regular opportunity at Anfield the Republic of Ireland captain was shipped out again after just six months.
The much-maligned trio of Ryan Babel, Andrea Dossena and Lucas Leiva's cumulative transfer fees equal £25.5million and they have added little more than inadequate cover for the Reds' top performers, while Italian Alberto Aquilani has been another big-money letdown so far since joining from Roma and has failed to provide the coherence in midfield supplied by Xabi Alonso, who left for Real Madrid.