CORVALLIS — Throughout fall camp, Brent Brennan peppered his inexperienced wide receivers with the same two words:"grow up."

A quick maturation was the only way to take pressure off junior Richard Mullaney, sophomore Victor Bolden and the tight ends, the Oregon State assistant figured. Malik Gilmore, Hunter Jarmon, Jordan Villamin and others needed to limit miscues and embrace opportunity.

A week into the Beavers' 2014 campaign, "grow up" hasn't left Brennan's vocabulary. Though film of Saturday's win over Portland State confirmed that the wideouts performed "OK," Brennan surmised, the box score highlighted areas of improvement. Gilmore, Jarmon and Villamin, three candidates for key roles this season, did not record stats against the Vikings.

That's partly due to the game's flow, of course. But it's worth noting that Gilmore, Jarmon and Villamin were seldom open Saturday. Sean Mannion, a veteran quarterback with a knack for targeting the best available option, only threw to the trio once. Late in the second quarter, a pass intended for Gilmore fell incomplete.

Slotback, where Gilmore and Jarmon traded first-team reps much of camp, is the Beavers' lone remaining spot with no clear starter. Brennan had hoped on-field performance Saturday would determine a winner.

Without any production to judge, though, the competition is leaking into Week 2. At Hawaii on Saturday, Jarmon will again rotate in after Gilmore.

"I'd really like to see somebody just step up and take it over," Brennan said. "I think that's what we're all hoping for, and I don't think that's been done."

Still, he is hardly ready to panic about a receivers group that entered the season opener with just one player — Mullaney — boasting more than two career starts. Gilmore, Jarmon and Villamin are still adjusting to the Pac-12 stage, Mullaney said. Strides will come naturally as they grow more comfortable.

OSU totaled 328 receiving yards Saturday, a mark that ranked 23rd nationally in college football's first week. Tight end Connor Hamlett proved a reliable target, hauling in five catches for 86 yards. Mullaney, running back Terron Ward and Bolden were solid complements with 55, 53 and 52 yards, respectively.

Who catches the passes is unimportant, Brennan noted. It's about being productive, even if running backs and tight ends are repeatedly among the top receivers.

Yet he understands that the young wideouts' development is critical. As weeks pass, opponents' game plans will evolve. The Beavers will then adjust their offensive approach, a sort of reinventing made easier when Mannion can utilize his entire receiving corps.

"Sean has great confidence in Hunter, Malik and all those young guys," offensive coordinator John Garrett said. "All of the practice reps, those are just going to stockpile and it'll translate over to the game."

Brennan realizes as much. But don't expect "grow up" to leave his vocabulary until young wideouts get open on Saturdays.