Salah is set to leave Liverpool this summer after nine years at the club as he prepares to wave goodbye to fans at Anfield one the last day of the campaign.
After a nine-year spell at Anfield, in which he has scored 257 goals in 435 appearances, it will be an emotional goodbye for the winger who established himself as a club legend.
At 33 years old however, Salah looks slower and his ability has certainly decreased in the past year which may have helped him call his time at the club.
Rooney believes this may be the case for the Egyptian who he compares to his own career.
"I think that's happened to Salah this season and Virgil van Dijk hasn't been the same this season. They are the leaders in the dressing room. It's hard for the other players to go and leave their mark or become the leaders.
"I don't think he (Van Dijk) will (leave) but you've seen players when they've stayed there for too long."
"The hardest thing for a player is to understand you may be not at the level you were. I did it at Manchester United when Zlatan Ibrahimovic came in and I wasn't playing. I wanted to play so I left straight away. I accepted it."
Salah departs Anfield having won two Premier League titles, and one Champions League crown. He will forever be a club icon but it’s clear he understands it is time to go.