The Egyptian was voted Footballer of the Year and PFA Player of the Year after scoring 31 goals but only struck once in his final nine matches last season and just three times in his last 16 amid questions if he would leave Liverpool while they could not agree a new contract.
But the forward signed a three-year deal in June and Van Dijk feels Salah will benefit from playing with a “free mind” now.
Salah scored one goal and played a part in two more as Liverpool beat Manchester City 3-1 to win the Community Shield on Saturday and Van Dijk said: “He’s under the microscope all the time. He obviously created that himself because he’s such a good player, but he shows that consistency all the time.
“Towards the end of the season, maybe April onwards, there were a lot of talks with the contract and stuff. We are all human beings and I think that affected him a little bit unfortunately.
“But he still showed a high level of quality. Now everything is sorted, he’s playing with a free mind, he’s happy to be here and I think everyone else is happy too.”