The Magpies lost 1-0 to the Baggies at The Hawthorns in what McClaren believes was an extremely unjust result.
The Toon boss suggested striker Aleksandar Mitrovic had won a penalty in the second half while indicating that a defeat of this nature was undeserving for his players who just cannot seem to get a lucky break at the minute.
"It is a blatant penalty, I have seen it three or four times and the referee when he sees it again will realise he has made the wrong decision. The defender has grabbed Mitrovic around the waist and has put him off his shot before we lost to a soft goal at the end.
"We have ended the first half of the season with a bit of consistently but have been unlucky with our last two results.
"I am more disappointed for the players because they are fighting and showing attitude and endeavour.
"I am interested to know if there were boos (from fans at the end) because I think the team went over and were applauded.
"Sometimes you don't get what you deserve in football and the last two games we haven't but we have to continue what we have been doing knowing - and I know - it will turn around."