Chad Warner said his side were guilty of allowing in several "soft goals".
"They ran a bit harder then we did too," he said.
Lee Moir scored TCOB's only goal.
Meanwhile, women's coach Colleen Baylis said the 14-nil margin was unexpected, although a win was.
"We thought we would win and not because we have moved into division two. We really did expect the Marist girls to put up more of a fight, although they have a relatively young, inexperienced side compared to ours. We are expected it to be much tougher next week when we play College in Palmerston North," Baylis said.
Scorers for Wanganui were Sophie Redmayne (4), Kate Tylee (3), Melissa Goss and Nicky Skedgwell two apiece and Carlotte Baker, Lucky Wilbur and Kirsty Carson one each.