Quarterback Johnny Manziel during a Browns practice this week. (Tony Dejak/Associated Press)

RICHMOND — It will be only the opening exhibition game, and it is likely to happen after the starting players already have exited. But this is Johnny Manziel. So the curiosity factor still will be ratcheted up Saturday night in Detroit when the rookie quarterback makes his pro football debut, preseason style, for the Cleveland Browns.

It could provide the first hint at Manziel’s ability, or inability, to succeed at this level. And, perhaps just as interestingly, it could offer the first glimpse of what the Browns and their first-year offensive coordinator, Kyle Shanahan, plan to do to attempt to get the best out of Manziel early in his NFL career.

Shanahan and his father Mike constructed the offensive system that helped to make quarterback Robert Griffin III the NFL’s offensive rookie of the year with the Washington Redskins in 2012. It was also the offensive system that led to criticism by some observers that Griffin was running with the ball too often and putting his chances of having a long and prosperous NFL career at risk.

Veteran Redskins players said this week they’re unsure if Kyle Shanahan will take a similar approach with Manziel as a rookie.

“Honestly I don’t know,” fullback Darrel Young said at the Redskins’ training camp in Richmond. “I don’t know what their plan is. I don’t know if they’re running the same offense. I just know Kyle is a hell of a coach. I know he’ll put his team in the best situation.”

Tight end Niles Paul expressed similar sentiments, saying: “Kyle is a great offensive coordinator. He knows how to use his quarterback’s strengths to his advantage. So I think we’ll see a lot of similarities. But Johnny Manziel and Robert Griffin are, in my opinion, two different quarterbacks.”

Paul said his observations of Manziel, a Heisman Trophy winner while at Texas A&M, as a college player were that Manziel’s improvisations were aimed at buying time to make throws rather than gaining yards regularly as a runner.

“He moves around but he’s not as fast,” Paul said of the comparison to Griffin. “He’s not as fast as Robert. He can’t do the things that Robert does. But he does create a lot of opportunities for his wide receivers. You saw that was evident in college when he was just letting those guys [receivers] go up and get it.”

The offense that the Shanahans crafted for Griffin borrowed elements from the college game, including the pistol formation and option running plays. Griffin thrived and the Redskins won the NFC East. But his rookie season ended with him failing to finish a playoff loss and then undergoing knee surgery. Griffin was unable last season to recapture his rookie-year magic and there was intense scrutiny on his relationship with the Shanahans. Mike Shanahan was fired after a 3-13 season. Kyle Shanahan landed in Cleveland running the offense for the Browns’ new head coach, Mike Pettine.

Young said the Redskins’ record in Griffin’s rookie season means that the approach taken with him was sound.

“We won games,” Young said. “So at the end of the day, yes [it was justified]. … You’ve got to play until you can’t. You can’t worry about injuries and stuff. You put yourself in a situation to win games and that’s what he’s good at. Let him be Robert Griffin.”

Manziel quickly has established himself as one of the sport’s most captivating and polarizing figures. He was the center of attention when he dropped through the first round of the NFL draft in May, being taken 22nd overall by the Browns. His propensity to hit a party or two was well chronicled throughout the offseason. Now it’s about whether he can prevail in a competition with Brian Hoyer to be the Browns’ starter. Hoyer is scheduled to start Saturday and Manziel is to play in relief.

“I think it’ll be fun,” Manziel said at a news conference this week. “It’ll be fun to mix it back up. This will be the first game setting since my last college bowl game. So it’ll be nice to get back on the field and play a game. Everybody’s happy when the season rolls back around. You’re out on the field actually having a live game going on.”

Pettine said this week it’s doubtful that Manziel will take any snaps with the starters Saturday. But he said neither quarterback was given a definitive number of snaps that he’ll play against the Lions.

“We’ve kept it pretty vague with them. … This game can go a lot of different ways, as you know,” Pettine said at a news conference. “I didn’t want to give them exact specifics or exact counts. You never know what can happen early on. I told those guys I’d rather them be prepared to play more than they think they’re gonna play than give them a number and then put them over.”