McDermott got the response he wanted after last week's 32-8 home defeat by Huddersfield but was still frustrated by his team's inability to finish off their opponents.
"We weren't great last week but tonight we showed a lot of resilience and a lot of grit to get the game," McDermott said.
"I didn't think we were great with the ball, although we had two clear-cut chances for tries and bombed them.
"We've a smile on our faces but it was a frustrating win. Defensively I thought we were strong and credit goes to Wigan, too. It was a tight game, I thought both teams defended each other out of the game."
The Warriors' defeat came at the end of a week in which coach Shaun Wane's father passed away, with the players wearing black armbands as a mark of respect.
"I lost my dad on Wednesday, which is sad," he said.
"I needed a distraction and wanted to get back in work as soon as I could.
"It was a poor finish to the week. I was proud of our effort but individual errors cost us.
"Leeds are a great team and you can't turn up here with ordinary errors like we did."
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