The common refrain this offseason from folks outside the USC program: “there’s only one ball.”

Under first-year head coach Lincoln Riley, USC drastically and emphatically reshaped the roster this offseason, utilizing the transfer portal to fill holes and bring star players from across the country to Los Angeles. The wide receiver room looks overflowing with talent. The running back group looks rather deep, as well.

But there’s only one ball, detractors will say. USC can’t possibly make all this work. Someone’s getting left out. Someone’s going to be unhappy with their usage. Not so fast.

The thing that impressed new USC tailback coach Kiel McDonald — an assistant with Pac-12 champion Utah last season — when he picked up Riley’s playbook was its versatility.

McDonald, who met with local media earlier this week, said the thing that makes Riley such a successful playcaller and offensive coach is his ability to mold to what he has.

“You’re out here making plays, those are the plays we’re going to call at the end of the day,” McDonald. “I think that’s kind of universal. I’ve seen his offenses over time, he’s had two great backs when they’re in 20 personnel. They’ve had an electric tight end, they’re in 11 personnel. They’ve got four wide receivers, they’re going to be in 10.

“He just does an amazing job of getting the playmakers the ball.”

At wideout, USC has Jordan Addison, Mario Williams, Gary Bryant Jr., Tahj Washington, Terrell Bynum, and Brenden Rice — to name a few. In McDonald’s room, USC has Travis Dye to lead the group. Dye was the Pac-12’s leader in all-purpose yardage last year. He’s expected to eat up the bulk of the backfield carries, but between Raleek Brown, Austin Jones, and Darwin Barlow can all provide a little something extra.

On Brown, McDonald said: “He’s a very good player, there’s no doubt about it. He’s just got to continue to get acclimated to the college game. He’s going to be able to help the Trojans for sure.”

On Barlow, McDonald said: “Darwin had a really good scrimmage as well. He made quite a few plays in the scrimmage. He’s just getting more comfortable in the offense. … I think he’s made a considerable jump from the spring to now.”

The team scrimmaged for the first time this past weekend. McDonald and the rest of the offensive staff got a nice look at what they have.

“You got a chance to see, are you breaking that tackle? Are you making that play, that spectacular play? We got a chance to see that,” he said. “So those guys that are making (those plays), forcing those (missed) tackles, making those plays down the field, obviously, those are the guys that are going to be playing for us.”

And McDonald said everyone in the running back room made a play or two. Snaps are pretty even across the board right now, he said.

Perhaps we’ll get to see quite a few looks when the Trojans open up the season against Rice on Sept. 3.