Vaeao, who battled injuries earlier in the year, has played in five games and has four stops on the season. He posted one tackle against Stanford. The d-lineman he replaced in the starting lineup, Matthew Bock, had four stops and was in on a sack against the Cardinal.
WSU's starting defensive line, like virtually the entire rest of the team, has seen significant changes over the course of the season. The WSU three-man front for the season opener was Steve Hoffart, Gauta and Bock.
Xavier Cooper took over one of the DT spots in Week 4 against Colorado and Vaeao started at the other spot last week. But Bock and Hoffart have continued to see turns in rotation - as have Toni Pole and Logan Mayes. Both Pole and Mayes have also started this season.
Vaeao was one of the headliners of the 2012 class despite his two-star ranking, with the American Samoa product committing to the Cougars over offers from Washington, Oregon State, Arizona, Colorado and several others.
He might be the only change to the starting lineup, but Leach said he would have more clarity on that later in the week.
Overall, Leach said he likes the improvement he has seen from the defensive unit. WSU allowed Stanford only 256 yards of total offense during last week's 24-17 loss.
"I think we're improving overall," he said, noting that BUCK linebacker Travis Long and linebacker Cyrus Coen have "played really well."
Leach also noted that safety Deone Bucannon has been consistent, while Cooper and linebacker Justin Sagote, a junior-college transfer, are improving each week.
"I've been kind of slaying my own dragons here," Leach said. "The biggest thing is you've got a competitive league. You just keep plugging away."
* CF.C managing editor Barry Bolton also contributed to this report.