Salah joined Chelsea from FC Basel in the 2014 January transfer window as a promising 21-year-old as Jose Mourinho hoped to add depth to his attacking options.
However, the Egyptian managed just 19 appearances in all competitions for the Blues as he remained a fringe player until a loan move to Serie A side Fiorentina at the end of the 2015 January transfer window.
An additional loan move to Roma followed before it was made permanent in 2016 as Salah started to find his groove in Italy, ending the 2016/17 season with 19 goals in all competitions.
The former Basel star's performances caught the attention of Liverpool who went to sign the 25-year-old earlier this summer and Salah has not looked back since.
He has already scored 15 goals in 20 appearances for the Reds, including 10 league goals in 13 games. He recently scored against Chelsea in their 1-1 draw over the weekend.
Salah's performances were a major talking point ahead of the visit of his old club and Ashton believes there were two key factors as to why he did not flourish as much at Chelsea.
"It [Salah's form] is [remarkable]," Ashton said, as quoted on Express. "I think maybe at Chelsea he was just a bit young when he went in there.
"I think he was (about) 20 when he went there, maybe it was a bit too much for him at that time. He's gone away to Roma, was fantastic there, and he's come to Liverpool and I think the way they play really, really does suit him.
"They like to break quickly, he's got other quick players around him."
Ashton is also impressed at Salah's all-round game as he is not only scoring goals for Jurgen Klopp's side but also helping by creating chances.
"I think he's surprised everyone with the amount of goals that he's scores and it's not only just the goals which are fantastic but the amount of chances he's creating for himself each game," Ashton added.
"I think that shows what a good player he is when you can get in the positions as often as he is."