Mitchell finally made his full Town bow in the 2-0 win at Southend last weekend after Sam Ricketts’ No.1 Steve Arnold suffered a season-ending hamstring injury.
Former Newcastle youngster Mitchell, 24, joined on loan from Derby in January but, while featuring in a couple of cameos from the bench, has not dislodged Arnold from his first-team perch.
Mitchell was largely untested at Roots Hall but impressed with his catching and kicking and is expected to keep his place for the equally important visit of managerless Scunthorpe on Saturday.
“I thought he came in with real confidence, he’s a top top lad who wants to come in and do well,” said Waterfall, who made it six goals for the season with Town’s second at Southend.
“He’s had to wait for his chance and he’s got it – unfortunately with Arnie getting injured – but he came in and grasped it with both hands.
“I thought he did really well coming into a big game like that to make his full debut.
“He did what he had to do, I don’t think he had many saves to pull off but his kicking was excellent. In the last 10 minutes I thought his kicking was excellent into the corners.
“It helps you see games out really well when he’s kicking like that.”
Waterfall has been playing in the centre of a defensive three for Town in recent months, with the excellent Ro-Shaun Williams and either Omar Beckles or James Bolton in support on each side.
Last summer’s signing from Lincoln City, who has made 47 appearances in his debut League One campaign, feels Ricketts’ system plays to all of Town’s defenders’ strengths.
It gives me license to go and win my headers,” added the powerful stopper.
“I’ve got Ro-Shaun and Omar with pace at the side of me. I think it’s worked well. I think we’ve played pretty consistently well.
“Results might not say that but I feel it’s the best we’ve played in that formation all season.
“I think the gaffer’s going to stick with it now till the end of the season. I’m enjoying it, it suits me, let’s me do what I’m good at and other people do what they’re good at.”