Miles' involvement in an altercation after the Super Bowl led to a suspension that kept him sidelined for all of spring practice. He was reinstated by coach Chris Petersen on May 14.
"I think we took some pretty hard action when things were still being decided," Petersen said Thursday at Pac-12 Media Days. "He didn't do anything with us football-wise [during the spring]. You have a brand-new staff teaching this and you take a guy out and give him nothing at that position -- it's pretty tough.
"And then we're also going to sit him for the first game. I think [Miles] will learn."
Miles, a redshirt sophomore, is widely expected to replace Keith Price as the starter , but Petersen has not officially committed to one.
"That quarterback position is wide open. It is," Petersen said. "We need to get [Miles] in there competing with those guys to see what he brings to the table."
Miles appeared in eight games off the bench last season and completed 37 of 61 passes for 418 yards with four touchdowns and two interceptions. For the opener, Jeff Lindquist and Troy Williams are the top candidates to start against Hawaii on Aug. 30.
Petersen said he has been pleased with Miles' behavior since suspending him in February.
"He's done everything right, without question, or he wouldn't be with us," Petersen said. "Guys make mistakes, we all know that, certainly in that age group. We always say that the age group we're dealing with, for the most part, is the dumbest age group in America.
"It just happens to be so public. Guys make mistakes, but the important thing is that we learn from it."
Former Washington receiver Damore'ea Stringfellow was charged with two counts of fourth-degree assault and one count of malicious mischief as a result of the same incident, has since left the team. He was not charged.