"We just made individual errors that cost us the goals.
"We're just not good enough off the ball at the moment."
Vanya Hodgkinson got a sole score for the home side, while Dana McCelland deserved better for some enterprising play on the wing.
With six regulars away, Calvert said the squad was able to take in three newcomers, one of them 15, who had the guts to come up from Saturday's local league to take part.
It has been a bugbear for the coach in 2018 where some who come down to watch on Sunday's will criticise or give opinions about how certain players should perform, but they won't "fight for the cause" themselves by joining the team.
"They pick themselves back up," he said of his squad.
"It would be easy to say, "I'm not winning, I'm not going to play', but they've got the best attitudes in Whanganui."
The draw does not get any easier as Football Whanganui next travel to meet table leaders Massey University on Sunday, trying to improve on their 8-1 loss on May 20.