Marquis has failed to score in his last nine matches – his longest barren run for the club – and missed a glorious opportunity to put Rovers ahead against Plymouth Argyle last weekend.
While admitting Marquis appeared to be lacking confidence in front of goal, boss Ferguson again cited the forward’s superb work rate as justification enough for his starting berth.
“John had a great chance, a great chance,” Ferguson said. “At the moment it’s just not going for him.
“But the amount of work he does for the team off the ball, you have to appreciate that.
“At the moment he is clearly short of confidence.
“It’s what strikers are all about. One minute they’re full of confidence.
“That chance goes in with his eyes shut last season.
“This year he is not scoring goals, he’s lost a bit of confidence.
“But he is working so hard for the team that he is doing a job for the team.
“I think the amount of work he is doing warrants his place in the team.”
Alfie Beestin partnered Marquis in attack against Argyle and scored his first ever league goal before being replaced by Alfie May.
Ferguson said he was disappointed with May’s performance off the bench and questioned whether he too was currently short of confidence.
He said: “Alfie May comes on, I don’t know what he was up to. It was just not good enough.
“That performance coming off the bench wasn’t good enough.
“Whether he’s lacking confidence I don’t know.
“The players are not silly. They know when they’ve played well or played badly.
“My job is to pick him up which I will do. Alfie will be fine. I’ve no real concerns about the boy.
“Whether he’s nervous or not, I’ll have a chat with him.
“To be fair, where he’s come from he should be the last person that needs to be nervous. He just needs to play with freedom and enjoy it.
“I have to make sure the players have confidence and there is one or two of them that I’ll have to deal with in the week.”
Rovers are today expected to confirm the signing of defender Shane Blaney from Finn Harps.