"The next three trainings we've got to keep their feet on the ground, finals are a different kettle of fish," he said on Monday.
In front of a good gathering of Metro stalwarts on Saturday, who were there to watch the double header with the St Johns Wanganui Metro Women also playing Feilding Old Boys-Oroua, the Colts led 40-0 at halftime and kept up the momentum.
Virtually all the points were scored by outside backs, with wingers Joey Devine and Cody Davy both getting hat-tricks.
Centre Matt Murphy got a try and popped over six conversions before handing the kicking duties to Devine, who got three conversions himself for a 21-point haul.
Francisco Field added his sixth try of the campaign, as Cosford is working with a large squad and is able to alternate between two sets of quality outside backs.
"That's what we've been trying to do [is] get it wide, it's too tight around the rucks these days," he said.
"Feilding Old Boys are the same situation – if we get it wide, we're away."
The Wanganui Metro Women completed their campaign with a 44-0 scoreline against them that was respectable, given leaders Feilding Old Boys-Oroua had beaten Kia Toa 41-18 and Kia Toa went on to destroy Metro 91-0 the previous weekend.
Metro will now play some post-season rugby in an effort to get the new team added game time, while there is also the upcoming Wanganui vs Horowhenua Kapiti women's representative match.
• The Metro Colts semifinal with Feilding Old Boys kicks off at Cooks Gardens on Saturday at 1pm.