The Premier League title holders sit in sixth place on the table and are in danger of missing Champions League qualification for next season.
Speaking to ESPN, Alisson said: "Our season is far, far below (what it should be). I think we realise that, we feel that, we are aware of that. For the quality of the team, for the size of Liverpool.
"But all the factors you mentioned about change, if you had only had one, it would have been very difficult. Because if you look at it, the team that won the Premier League last year and the starting eleven (now) are very different teams, even in terms of characteristics."
The tragic death of Diogo Jota has also been a factor.
Alisson also said, "We are experiencing emotional problems that go beyond human. Humans cannot handle it. Everyone handles it in their own way. We lost a teammate, we lost a friend and we have injury problems.
"Whatever you can say, problems that can arise in football, most of what can happen in terms of challenges, we have faced this season. But we never use that as an excuse. We try to do our best."