"The groundsman Jason Booth and his staff did a fantastic job to get the game on.
"We had to fight for it," added McDermott. "Hull KR came with a lot of resilience. They didn't go away. I thought their intensity would drop off but it didn't.
"We had some defensive laps but other than that, it was good. What I wanted as a coach we got out of it. I would have liked us to play a bit better but give Hull KR some credit for that."
Brett Delaney had the distinction of scoring the first try of Super League XVII and others came from Brent Webb and Danny McGuire, but it was the 20-year-old Watkins who stole the show.
"There is a lot more to come with him," said McDermott. "I thought some of our composure and timing showed we clearly have got some work to do, but give some individuals the ball in some decent positions and they come up with the goods.
"He was very potent and, while he rightly got the man of the match, I also thought Jamie Peacock was strong to say he hadn't played a warm-up game. But the work that Carl Ablett got through in his second stint had a big contributing factor in how the game turned out for us."
Hull KR coach Craig Sandercock added: "I'm pretty proud of my boys, considering the penalty count and the fact we spent the whole game defending our own line," he said.
"I thought we gave a good account of ourselves. Saying that, I thought Leeds too good on the night.
"For the first 65 minutes I thought we were outstanding and, if a couple of things had gone our way, I might be a bit happier.
"But they didn't and Leeds are a first-class side. You lack concentration or miss a tackle and they hurt you. That's why they are the champions.
"The scoreline probably doesn't indicate the effort we put in because it was six tries to four."