Salah joined Chelsea from Basel, swiped away from under the nose of Liverpool, in January 2014. But he played less than 20 times in all competitions, before joining Fiorentina on loan only a year later and leaving permanently for Roma by 2016.
For Hazard, it was a question of convincing the manager and competing for places against established players.
"He's a top, top, top player. He did not get his chance at Chelsea maybe because of the manager, because of the other players? I don't know," the Belgian is quoted as by Sky Sports.
"He has quality but in that period I remember we had me, Willian, Oscar, so for him it was not easy.
"He is a fantastic striker and this season he has scored a lot of goals. It is always good to play against a friend but Liverpool is not only about Salah. They have a lot of quality players."
Salah's form at Roma saw him make the £34m switch to Liverpool in the summer and he has hit the ground running in the Premier League second time around.
Ex-Chelsea player turned pundit Pet Nevin has told the Daily Express similar about a lack of chances being the reason for his relative failure at Stamford Bridge.
"The key thing with Salah first time round at Chelsea was that he was a year or two younger and still learning the game," the retired winger said.
"In front of him at Chelsea in his position were players like Eden Hazard, Willian, Oscar, Victor Moses and Andre Schurrle. He was not playing at anywhere near that level at the time.
"It was a case of right player, wrong time. But they knew he had something. He had pace and a great touch. Now, he is under another manager in Klopp who is absolutely ideal for him.
Liverpool Fans Crown Red-Hot Winger Mohamed Salah Their New 'King' on Wikipedia https://t.co/ya3lfffllh— LiverpoolPro (@LiverpoolPro) November 21, 2017
"He has Sadio Mane, Philippe Coutinho and Roberto Firmino in and around him - and there are not many better attacking units than that. Now, the fit is right."