A tight first half ended goalless but, when Lomas made 11 changes after the break, including trialists Nicky Shorey, John Paintsil, Lee Cook and Lee Croft, the Bees took control through goals from Sam Saunders, Paul Hayes and Stuart Dallas.
"Firstly it was about protecting those players who you want to be playing for you at the start of the season," said Lomas.
"We were competitive in the first half but we couldn't afford to give those lads too much longer at this stage.
"That's one reason we've brought some extra bodies in, to train with us and have a look at them.
"With so many changes and some unfamiliar faces in the second half we were quite disjointed, and while you don't want to get heavily beaten it wasn't a total shock for those reasons."