Daniel Agger has denounced Fernando Torres for showing a lack of "respect" for Liverpool by joining Chelsea but admitted the Merseysiders' dismal start to the season had contributed heavily to the Spaniard's inconsistent form.

The Denmark centre-half has been a key member of the Liverpool side revitalised under Kenny Dalglish, rising to sixth in the table and six points from the fourth Champions League qualification place. The arrival of the £23m Luis Suárez from Ajax and Newcastle's Andy Carroll for a club record £35m could add even more impetus, potentially offsetting the £50m departure of Torres to Stamford Bridge.

The Spaniard's move, triggered by a desire to leave Anfield, frustrated Agger. "It is unacceptable to play for one of Liverpool's arch rivals," he said. "For a Dane, it's about having respect for the club you play at. I am proud to be able to pull on my Liverpool jersey and will never go to another club in England. I would never go to Manchester United or Everton, for example. It's about a form of respect for the club.

"I suppose Liverpool got a lot of money for him and, if the player doesn't want to be there any more, there is no reason to keep him. I should say I think everyone at Melwood liked him and still do, because he is a good guy and we wish him all the best in a blue shirt – except against us."

Asked why Torres's form had been so stodgy in the first half of the season, Agger said: "That is a big question, isn't it? How to explain that ... Look at the team – we played awful, we were shit. And he is a part of the team. When every element of the team plays well, he plays a lot better. It is the same for everybody – for me, for Stevie [Gerrard], everyone. When the team are performing, look at every single player and he is playing better. But when we are losing, everybody is on top of us. Everybody is playing poorly."

Liverpool have rediscovered their poise in recent weeks, with Dalglish overseeing a run of four successive victories, the last of which came at Torres's expense last Sunday. "A big part of it is down to Kenny and [the coach] Steve Clarke," said Agger. "They have made a major difference. But it is also something to do with confidence, because we are the same footballers. Confidence can win games and, somehow, Kenny and Steve have put the confidence back into the players. It is looking good, but there is still a long way to go."

Liverpool's assistant manager, Sammy Lee, attended Denmark's defeat to England in Copenhagen to watch Agger's international team-mate Christian Eriksen. The impressive 18-year-old midfielder is attracting interest from several leading clubs, including Arsenal and Milan, but believes his apprenticeship is best served by staying with Ajax and that he may not suit a move to the Premier League.

"I think I'm going to play in Ajax until my contract expires," said Eriksen. "There are a lot of young players who are busy looking at other clubs but that's not the way I think. There are still lots for me to learn and improve, and I can do that in Ajax, which is one of the best clubs in the world to develop talents.

"Every time Ajax are playing there are clubs watching me. So, yes, Liverpool have probably seen me, but I am not spending time wondering about it. No matter what, the Premier League is not the most obvious place for me to go. I'm not sure that I've got the physical ability to play there. Serie A or La Liga would suit me better, but it [a transfer] is not going to happen now."

Dalglish has rejected a claim that Carroll could miss the rest of this season with the thigh injury that has delayed his Liverpool debut. The forward has not played since 28 December but Liverpool's caretaker manager insisted: "We said right at the beginning that it will be a few weeks. There is nothing sinister in it.

"He has been thoroughly checked over, he is progressing well and I think whoever made that assertion has got a good chance of being wrong."

The Liverpool midfielder Jonjo Shelvey has been ruled out for 12 weeks with a knee tendon problem.