"Then we sort of dropped off a little bit, Feilding scored a goal which I was really disappointed about."
Whanganui led 2-1 at halftime, during which Calvert told his team to get the ball to the strikers more.
They did just that and came out firing again in the second half, scoring another two goals in the first 15 minutes and then finishing the job with two more.
"Their back four couldn't get anywhere near our attacking players. We absolutely had them and if it wasn't for their goalkeeper, we would have scored a lot more," Calvert said.
"In all honesty, I'm a bit disappointed that we didn't get to double figures. That's how good our attacking forward play from the back was."
Calvert joined the team as coach during the pre-season last year and during their two years in the league, they had managed only one win and one draw each season
Calvert said the biggest difference in 2019 is that there is competition for positions within the squad.
"At the moment we're building squads of 16 and keeping players out of the team. We brought in new players who have automatically brought in quality and the right attitude.
"The existing players from the last couple of years have seen that and picked up their games. They've looked after themselves a lot better coming into this season."
The sidelines were lined with spectators as more than 80 supporters turned out to watch the locals play at Wembley Park.
Calvert hopes to see more of the same when his side take on third placed Massey University FC there on May 5 kicking off at 1pm.
He said he wants to turn Wembley Park into a home fortress.
"What was great yesterday was that there were 80 plus people who had come to watch women's football on a Sunday.
"Wembley was packed with cars, there were loads of people watching and it gave a big signal as to what we can actually do with women's football."
Before that, the Whanganui team are set to challenge fifth placed Taradale AFC in Napier on April 28 at 1pm.
