Johnston, who joined Liverpool in 1981 after a spell with Middlesbrough, faced a midfield battle himself after joining the Reds but claims mental strength and persistence is key to making an impact.
"It gives me great pleasure to see lads come through tough patches like they have," Johnston remarked, following the announcement that Liverpool will play in Australia for the first time in July. "I think there is a lot to be said for Brendan Rodgers' style of management that he has managed to get Henderson and Downing showing the kind of form they have.
"I think, personally, people, and even managers, underestimate the mental side of football. I really do. Changing clubs is a huge thing, whatever your age. It's a major upheaval, and that's just the off-field stuff.
"Then there's the added pressure, the expectancy, the media spotlight. It all piles up onto players. It can be a downward spiral if you don't start fast at a new club."
Johnston made over 250 appearances for Liverpool and sympathises with Henderson and Downing, having gone through the same process to establish himself in the Liverpool side before a successful spell which saw him win trophy after trophy on Merseyside.
"It can take time to settle down after you move," he admits. "I experienced that first-hand, and I know all about how hard it can be to win people over. I was never the manager's favourite at Liverpool, I had to work hard to prove my worth to the team, and it has been the same for Jordan and Stewart.
"Liverpool fans appreciate hard work. They are knowledgeable and they can see if someone isn't giving 100%. Jordan and Stewart will know that too, and they have had to give everything they have to try and turn things around.
"I have great respect for them, coming through the tough times and coming out the other side stronger. I also think that Brendan's style deserves a lot of credit. Replacing Kenny Dalglish was always going to be a huge ask, an impossible job even but Brendan has come in and done some good things.
"I think things are looking good, personally. It is not perfect, and it will need more hard work, but I think the signs are promising."
Click here to see a photo gallery of Craig Johnston's time at Anfield>>