Salah's been the focus of attention this season, as the Egyptian player has not shown the same remarkable brilliance he displayed last season during Liverpool's journey to defend their Premier League title.
Former Manchester United stars Wayne Rooney and Paul Scholes were among Salah's most vocal critics, accusing him of work ethic, while a £65 million deal to sign Bournemouth's Antoine Simeone was floated as a possible replacement.
Barnes told the Mirror Football in response to a question about the Egyptian star's level: "There are many aspects to the issue and the decline is not just related to Salah's performance. Liverpool are playing differently this season. If you think about the way Liverpool used to play, you would realize that the passes were coming from Trent Arnold or the rest of the players to Salah."
He added: "Now with players like Florian Wirtz, Ekitiki and Isak the way things have changed. Once we improve our harmony we will be fine. We are just going through a difficult start and it is a coincidence that Salah is 33 years old so some people mix things up and blame it on age."
The Liverpool legend added: "The opposing teams are defending more deeply against us, and this makes things more difficult. The problem is not just Salah, but a combination of the team's changing style, the new players, and the way the opponents play. I am not worried about Liverpool's future success, but we need some time to get back to the level of the last three or four years."
It is worth noting that the 33-year-old Liverpool star has scored five goals and provided three assists in 16 appearances for the Reds so far.