Harris’ men crashed out of the tournament with a 24-16 defeat to USA in Wrexham at the weekend, meaning they now cannot make the quarter-final date that had been set up for them to make a return to the Racecourse Ground on Saturday week.
Harris said: “Pride is important and the players are very proud people.
“The game of rugby league is a professional game, and over the next seven days the players have to show their professionalism.
“It was a bad result (against USA). We had 20 to 25 opportunities in the game to score points and score tries but we took a lot of wrong options.
“A lot of our decision making was poor, and ultimately, our side is not good enough to be playing at 60% capacity.
“USA are an extremely good side that have got a lot of experience and a lot of players who play at a good standard, and if you don’t perform to your best, you will come unstuck against them.
“It’s a positive that so many people came out and supported us in Wrexham. We’re not where we want to be yet, and everybody knows that, which is why we’re investing in youth.
“It is frustrating that we haven’t played to our potential in the two games so far.”