The Baggies had been in cruise control after Belgian international striker Romelu Lukaku had put them 2-0 up. Reading appeared down and out but they conjured a remarkable finish to the game with three goals in the last nine minutes from Jimmy Kebe, Adam Le Fondre and Pavel Pogrebnyak.
The result leaves Reading three points off safety and McDermott believes the teams directly above them - including next weekend's opponents Newcastle - will be nervously looking over their shoulders. "I think so. We are one game, or three points, from the team above us," McDermott said.
"People automatically wrote QPR and Reading off. We have been written off for ages, since we won promotion. It is nothing new to me. Since I got the job we have always been written off.
"But we got that first goal and you saw a side that showed real belief and character. That is a game that will go down in lot of peoples' memories."
After a run of seven successive defeats, Reading have pieced together two wins and a draw from their last four games in the league. And it has come about with a change of approach from McDermott.
"I have learned a lot about this division in the last four months," he said. "It is an incredible division. Sometimes you can't be gung-ho, you can't go for it like a boxer because you will get knocked out.
"That is what happened to us early on in the season.
"You set the team up the best way you possibly can, you stay in the game and if you can win it late on, you win it late on.
"You have to (contain teams). It's a case of staying in the game. We can't give away goals in the first half."