"I think it's got a chance to be maybe the most talented team that we've had in the last four years," said Riley, who joined the Sooners as offensive coordinator in 2015 and succeeded Bob Stoops as head coach prior to last season. "I think if this team reaches its potential then we can play with [anybody] and we can beat anybody."
Oklahoma has reached the College Football Playoff in two of the last three seasons. But on both occasions, the Sooners had Mayfield at quarterback. After capturing the Heisman, Mayfield went on to become the first overall pick in the NFL draft.
According to Riley, Oklahoma, with several other key players returning offensively, could remain a playoff team even without Mayfield.
"I do think we have that capability," Riley said during Big 12 media days. "Now, having that capability and getting there are two different things. It takes so many things to go your way. You're going to have to win some tough games, you're going to have to stay healthy. ... But I do think the talent is there."
That includes at quarterback.
Though Kyler Murray continues to be the overwhelming favorite to take over for Mayfield, Riley reiterated Monday that Murray hasn't officially won the quarterback competition yet over sophomore Austin Kendall.
Still, Murray's skill set could be one of the primary reasons why the Sooners could become a playoff contender again. A former five-star football recruit, Murray was taken ninth overall by the Oakland Athletics in the MLB draft last month. He will remain with the Sooners this season, then join the A's to move forward with his career in baseball.
"Kyler's athleticism jumps off the screen pretty quickly," Riley said. "You don't see that often in his position, but he's a better thrower than he gets credit for."
Riley did admit that Oklahoma's talent defensively hasn't matched up with some of the top units in the country in recent years. The Sooners ranked 58th nationally in defensive efficiency and surrendered 54 points in an overtime playoff loss to Georgia in the Rose Bowl.
But even though Oklahoma didn't have a single defender make the preseason All-Big 12 team, Riley said he believes the Sooners are rapidly trending up on that side of the ball.
"We feel like we're in the process of making a pretty good move there," he said. "Some of our best talent defensively right now is from our freshman and sophomore classes. We're probably only going to play with maybe one, maybe two seniors. I think that shows we've been on a nice run recruiting over the last couple of years. We're building. ... But I don't think we're far off from being the kind of defense that we want to be."