The Brisbane Roar striker has scored 13 goals in 21 A-League games this season but was not included in Postecoglou's 30-man squad for upcoming FIFA World Cup qualifiers against Iraq and the United Arab Emirates.
In fact, the only out-and-out strikers in the squad are Tomi Juric, who has just returned from a knee injury, and the ageing Tim Cahill, who has been used sparingly by Melbourne City in recent weeks.
Postecoglou said Maclaren was still in the selection frame due to Australia's lack of depth up front but simply hadn't done enough to earn a call-up.
"I don't think he's been as consistent this year as he was last year," he said.
"It's not just about goals, it's about each player and their game evolving - probably Adam Taggart is in a similar boat.
"You just want to see their game continually evolving because we know that international football is different from club football, anywhere around the world.
"Jamie's had some inconsistencies but the good thing is I thought on the weekend he played really well.
"Apart from his two goals, I thought he got into good positions a number of times and probably could have had a couple more."
Maclaren, 23, is off-contract at the end of the season and there is still no indication as to whether he will stay with the Roar, move to another A-League club or try his luck overseas.
Postecoglou said he didn't care if the uncertainty was affecting his football.
"I'm the national coach, all I'm looking at is what's been produced on a weekly basis," he said.
"I'm not there to sort out their club careers or club situations. That's up to their coaches and themselves.
"From my perspective, I'm more interested in what's happening when they get on the field of play and that's what I'm measuring."