Tulane’s running back rotation was already deep.

Now, it’s bordering on complicated.

After third-stringer Dontrell Hilliard racked up 208 rushing yards, 115 receiving yards and three touchdowns in the past two weeks, what began as a two-man operation has expanded into a trio as the Green Wave (3-6, 2-3 American) prepares to face Memphis (6-3, 4-1) at 2:30 p.m. Saturday in Yulman Stadium.

“This young Dontrell Hilliard kid — now I’m going to admit when I was wrong,” Johnson said. “Guys, I was wrong and (running backs coach) David Johnson was right. He kept telling me to play him more, and all of a sudden this kid is playing absolutely out of sight.”

Ankle injuries limited Sherman Badie and Lazedrick Thompson during a loss to Cincinnati two weeks ago and last week’s 31-24 win over Houston, opening the door for Hilliard to take the bulk of Tulane’s offensive snaps. However, with Badie and Thompson practicing at full speed Monday, the equation of three running backs and one football becomes a bit convoluted.

When fullback Dante Butler, who averaged 5.9 yards on eight carries against Houston, is added in the mix, it becomes even more problematic. But there doesn’t seem to be any strife among the backs themselves.

Badie and Thompson were among Hilliard and Butler’s most vocal supporters on the sideline, and each has stressed the importance of balance when asked about the cluttered backfield.

“Those guys kind of police each other, and they’re very positive in their own room,” quarterback Tanner Lee said. “They pull for each other and they’re OK with being a six-headed horse. If you just hear them talk about themselves and talk about each other, you can tell they’re happy for one another.”

In the end, it’s a problem the Green Wave aren’t going to spend much time complaining about. In past years when Tulane’s starting running backs were injured (like Matt Forte, Andre Anderson or Orleans Darkwa), the limited depth behind them resulted in a noticeable drop-off in production.

It’s why Johnson said he’s “shocked” by the young, quality depth that’s emerged, but isn’t concerned about how to use it.

“You love to have a running game,” Johnson said. “If you have 80 or so plays and if they can get 20 plays each, that’s kind of what you want. These guys are so young, and you package stuff up for certain guys. I don’t think we have guys that are great at any one thing.

“(Thompson) is the guy who you use if you want to pound at a defense and soften them up. Sherman is the guy who is lightning and is going to run it. Dontrell kind of does it, all and he reminds me of (Saints running back) Pierre Thomas, who has great balance and body control. I think you can fit all of those guys in.”

Penalty problem

Johnson wants consistency in the rule which has taken out two of his defense’s best players over the past two weeks.

Targeting, a penalty adopted last year, was called on defensive end Tyler Gilbert and safety Darion Monroe in consecutive games, leading to first-half ejections.

Although the penalty now triggers an automatic review, Johnson said he still isn’t clear on what constitutes targeting and what doesn’t. In a 47-13 loss at Duke earlier this year, officials waved off two cases of targeting Johnson said he thought were obvious.

Then questionable targeting calls on Green Wave defenders were held up later in the season. Tulane was the first team in the country to be levied with the targeting penalty, when Lorenzo Doss was flagged in a 2013 season-opening win over Jackson State.

“I’d just like us to have cleaner definition of all of it, just to make sure we’re doing all of the right things,” Johnson said. “We need to go into the offseason and re-evaluate the rule to make sure we’re getting accomplished what it’s supposed to accomplish.”

Sold out

Tulane will host its second sellout of the season Saturday afternoon.

Boosted by homecoming festivities, the matchup against Memphis will join the home opener against Georgia Tech as the biggest crowds in the young history of Yulman Stadium.

Standing-room-only tickets are still available at $35.

“I want all of them to play well because for homecoming,” Johnson said. “Everybody is going to be here and it should be a packed stadium.”