Hall demonstrated his uncanny ability to score from near-impossible positions as he twice squeezed over at the corner for crucial tries to condemn the Wolves to a fourth defeat of the season.
"I know it's a bit of cliche to say there are not too many people in the world who could get the ball down in those circumstances but I think it's accurate," McDermott said. "You could say the same about (Warrington winger) Joel Monaghan. It's great for Hally and it's great for us that we've got him in our team."
Leeds were also indebted to full-back Zak Hardaker, who made a big impact on his return from a six-week lay-off with a fractured thumb, creating the position for Paul McShane's second-half try with a spectacular 60-metre break and pulling off trysaving tackles on Stefan Ratchford and Micky Higham as Warrington staged a fightback.
"Welcome back Zak," McDermott said. "He's clearly good with the ball and he was good defensively as well.
"We weren't that great defensively in the second half and he saved our blushes a couple of times. I didn't think we were overly dominant. I thought there were periods where we looked good but there were periods where Warrington had momentum and a combination of desperate defence by us and some lost ball by them kept them out."
Warrington coach Tony Smith revealed after the match that veteran half-back Lee Briers has been given the go-ahead to resume playing after being out since the second match of the season with a neck problem - and he admits his return cannot come soon enough.
"Lee has been given the green light to return to playing and so it won't be long before he's back," Smith said. "He's one guy who has got a kicking game and we needed that. Leeds' kicking game was chalk and cheese compared to ours. I thought Kevin Sinfield's kicking was terrific."
Warrington trailed 20-12 at half-time and, although Joel Monaghan scored the second of his two tries and Ryan Atkins also touched down just before the end, Smith could not hide his disappointment. "I thought our first half was dreadful, the worst we've produced for a while in terms of energy," he said.
"I didn't think they were outstanding, just businesslike, and they did what they had to do. If they had been on their game, they would have smacked us. They were okay but we were well below okay. We just didn't test them, we didn't put enough on to trouble them, although we lifted a bit in the second half. I was really disappointed with the manner in which we conceded a couple of our tries."