This is, Patrick Roy says, part of the normal process for young players. They want to stick in the lineup, they assume the way to do that is to put up numbers, so they make the sort of mistakes Cal Ritchie made Tuesday night in Detroit.

The 20-year-old Ritchie has, mostly, avoided those sorts of games so far in his rookie season. One of the reasons he’s stuck with the Islanders instead of shuttling between New York and Bridgeport is because he’s proven trustworthy and sound in his own zone.

The 3-2 loss to the Red Wings was an exception, and he knew it.

“I thought last game was pretty bad,” Ritchie told The Post Friday morning before notching an assist in the Islanders’ 4-1 loss to the Canucks. “Did video yesterday. Try to learn from my mistakes and continue to grow my game.”