The Blues had 22 scoring shots to half-time, and had led the Lions by 13 points at the main break.
"They were very good in the first half or we were very poor, whichever one, but fortunately we took our chances, that kept us in touch on the scoreboard," Matthews said.
"We were a bit sickly in terms of stopping the opposition from scoring (in the first half), which is one of the things we're trying to build our game on and we've done that reasonably well, but not tonight.
"Fortunately we got goals ourselves."
Matthews said he'd always suspected the Blues might fade late in the game, given they had a match in Perth last Sunday and a day less than the Lions to prepare.
"It was a short week for them after coming off Subiaco, I was always hoping that would mean they would have a tough game to play the game out strongly," he said.
“We've been playing all our games out strongly, so I was confident in that."
