CHARLOTTE, N.C. -- Christian McCaffrey's only direct work with the Carolina Panthers since last month's rookie camp came Saturday ... at a bowling alley.

Yes, the eighth pick of the NFL draft was allowed to hit pins with other Carolina players against the staff at head coach Ron Rivera's charity fundraiser, but he can't take hits from them until June 14.

And Rivera called the league office just to make sure that was all right.

The do-it-all running back out of Stanford falls under the antiquated rule that prohibits draft picks from participating in offseason workouts other than rookie camp until their school year ends.

They can't even be in the team facility.

It basically penalizes players who attend schools on a quarter system, which typically end much later than those on a semester system.

It doesn't matter that McCaffrey didn't enroll for the final quarter, either.

The rule still applies.

That means McCaffrey's first work on the field with the Carolina veterans will be June 14, the second of a three-day mandatory minicamp.

He'll get exactly two days with them before taking five weeks off before training camp.

"It sucks," McCaffrey told the team website during Rivera's event. "It's really tough."

It's a rule designed to encourage NFL prospects to finish their school year and graduate if that is their choice, without the pressure of having to attend team workouts.

But it doesn't take into account players like McCaffrey, who chose well before the draft not to enroll for the final quarter. It also doesn't take into account players who have no chance to finish their degree on time because they leave school a year or more before their academic work can be completed.

Rivera would like to see the rule adjusted.

"I just think if a young man on his own is not going to enroll, don't hold that against him," he said after Monday's workout. "You don't know who you're going to get through the draft. If those young men decided on their own, then they're being punished for something that is their choice.

"It really only hurts the player. He's got to come in [late] and learn and grow and fit in."

The Panthers have been through this before, most recently with 2015 first-round pick Shaq Thompson. They are doing the same things with McCaffrey that they did with the former Washington linebacker, keeping him up to date as best as possible through Skype.

"That's the rule," Rivera said. "Until something changes, we've got to follow it."

McCaffrey told the team website that he has been working out in Denver during the day, watching Rockies games and reviewing the playbook at night with running backs coach Jim Skipper.

"He'll quiz me over the phone and then I'll go over everything, and he'll tell me what to learn for the next day," McCaffrey said.

"You can still get the plays down and get good training when you're home, but nothing will ever compete with actually getting the reps on the field, being with the guys."

The time McCaffrey has missed has been spent getting second-round draft pick Curtis Samuel and other rookies more up to speed. Like McCaffrey, Samuel plays multiple positions.

Samuel is a slot receiver first and a running back second. McCaffrey is a running back first and then a slot receiver.

Both are dynamic additions to an offense trying to evolve to depend less on quarterback Cam Newton as a runner.

What McCaffrey can't develop over the phone or on Skype is camaraderie. He got a taste of that at Rivera's charity event to benefit the Ronald McDonald House of Charlotte.

McCaffrey tweeted Sunday that he can't wait to get back on the field.

Can't wait to step back on the field. #TunnelVision🤐 pic.twitter.com/44CHbSdu5I — Christian McCaffrey (@CMcCaffrey5) June 4, 2017

Then, on Monday morning, as the Panthers returned to the field for voluntary workouts, McCaffrey returned to Denver on a plane.

"It was good to see him, too," Rivera said. "He got to spend time with the team more than anything else. That's the one thing he also misses, that chance to bond."