Fernando Torres has identified the sale of Liverpool's "engine", Xabi Alonso, as one of the principal reasons for the club's struggles this year. The Spanish striker also said the club's current team were not strong enough mentally to overcome a poor start. Yet despite his damning analysis he said Liverpool could recover with "a vengeance", with Rafael Benítez as manager.

In a frank assessment of a miserable season at Anfield, in which Champions League qualification is in jeopardy and when doubts have been raised over where Torres, Steven Gerrard and Benítez will be next term, the Liverpool striker blamed last summer's transfer strategy for much of the club's problems.

Torres admits to witnessing parallels between Liverpool and Atlético Madrid, the boyhood club he left in frustration in 2007, and cites the £30m sale of Alonso to Real Madrid, Alvaro Arbeloa's £3.5m move to the same club and Sami Hyypia's transfer to Bayer Leverkusen as causes of the club's failure to build on last season's second-placed finish in the Premier League.

In an interview with the Spanish sports magazine Don Balon, Torres said: "There have been various important factors, like the fact that we were so far off the top of the table so quickly. That killed us psychologically and has stopped us changing the situation. After that, injuries hit us pretty hard and we have felt that a lot. After a good season last year, the team needed certain reinforcements and keep the squad together, but circumstances dictated that we had to sell players and everything got messed up.

"The sale of Arbeloa, Hyypia and Alonso was an important loss. Alvaro was a player who did a vital job for us, always played to a high level and his flexibility was a huge bonus. Sami may not have played every week but he was a 10 out of 10 on and off the pitch, bringing calm to the ground and having everyone's admiration.

"And Xabi … players like Xabi are very rare. He was the team's engine and you know that when you change an engine, it takes time to work again."

The Europa League represents Liverpool's last chance of silverware this season and Torres, who will be fit to face Benfica in the quarter-final second leg at Anfield tomorrow, concedes there are similarities between recent disappointments and his ultimate disillusionment at Atlético. He added: "It's difficult to compare [the two clubs] because the level of expectation and the sort of objectives we have are totally different, as much in a personal sense as a collective one. But, yes, you could say that there have been certain situations that look similar, above all in this last year."

Torres's comments may heighten speculation over his Liverpool future, although the 26-year-old has repeatedly said that he wants to stay at Anfield, providing the squad is strengthened this summer. The striker believes Benítez will remain as Liverpool's manager and does not consider the club to be in terminal decline.

"Rafa signed a five-year contract last summer because he wants to improve the club. So I think that this new era of Rafa's is only just starting," he said. "Big clubs in Europe always go through difficult spells where it appears as though there is no light at the end of the tunnel. But because they are big clubs, they always come back and they do so with a vengeance. It is just a matter of time."