For NFL scouts and coaches ready to observe University of Georgia’s Pro Day, running back Keith Marshall is still quite the mystery man.

Despite a fine showing of speed and strength at the NFL Scouting Combine in February, there are several questions about Marshall and his viability as a pro prospect that he can answer Wednesday.

The Atlanta Journal-Constitution interviewed two NFL two scouts and a running backs coach about Marshall on the condition that they would not be revealed, hoping that would allow them to speak frankly about his NFL prospects.

While the consensus was that Marshall had a strong combine, the comments ranged from “the sky being the limit” for Marshall to whether he was even “draftable” because of his medical background.

At the combine, Marshall ran the 40-yard dash in 4.31 seconds and bench-pressed 225 pounds 25 times, which were both top marks for a running back.

However, at Georgia’s Pro Day, Marshall has to complete his workout. The scouts noticed he didn’t do any change-of-direction drills at the combine. So, all he really proved was that he can run really fast in a straight line and that he’s strong.

“He didn’t do the broad jump,” NFC scout No. 2 said. “He didn’t do the short shuttles, the long shuttles or the three-cone drill. That’s something that he’s going to have to do at his Pro Day.”

If Marshall backs out of those drills, “that’s a red flag,” NFC scout No. 2 said.

Marshall, a former five-star recruit, got off to a dazzling start to his career at Georgia in 2012. He rushed for 759 yards and eight touchdowns in 14 games, with one start.

“A lot of people don’t realize that before there was a Todd Gurley, there was a Keith Marshall,” the AFC running backs coach said. “Once upon a time that kid was pretty darn good.”

Injuries marred his college career after the good start.

“He just really never got healthy,” NFC scout No. 2 said. “Anytime that you’re coming off an ACL, especially that first year back, you’re going to be a little tentative because you’re scared. You don’t want to tear it again.

“Not too many people are Adrian Peterson. Just freaks of nature. It seems like after that knee, (Marshall) always had something with his right leg. All of his injuries were with his right leg. It was nothing with the left. He had a right knee ACL, right knee patellar, MCL sprain, ankle sprain and hamstring. That right leg has been giving him problems since 2013.”

Marshall, who could have returned for a fifth season at Georgia, finished his college career with 1,379 rushing yards and 12 rushing touchdowns. He’s projected as the 16th-best running back in the draft and slated to go in the fifth or sixth round of the draft by nfldraftscout.com.

“On his Pro Day we want to see the change-of-direction drills,” NFC scout No. 1 said. “That kind of stuff will be big just to make sure it’s not just a straight-line thing.”

Since the combine, the scouts have watched Marshall’s game tape. Other than 2012, it wasn’t pretty viewing.

“The most important thing is what you see on tape, especially at the running back position because so much of it has to do with vision and instincts and being able to make people miss in the hole,” NFC scout No. 1 said.

Alabama’s Derrick Henry and Ohio State’s Ezekiel Elliott are considered the top two running backs in the draft.

“It’s obvious that Derrick Henry is the big power guy,” NFC scout No. 1 said. “He’s got some long speed, and he’s a long strider, but he’s not nearly as explosive as Keith.”

Most project Elliott to be the first running back selected.

“I wouldn’t put him the class with Ezekiel Elliott,” NFC scout No. 1 said. “Ezekiel has better short-area burst to get through the line of scrimmage.”

But Marshall’s medical history may drop him out of the draft completely.

“For me, I’d rather have him as a free agent,” NFC scout No. 2 said. “If you draft him, it’s risky taking a guy that’s not been healthy since 2012. I don’t know if you want to waste a draft pick on a guy that you don’t know if he’s going to be healthy and he hasn’t had a lot of production. I’d rather have him as a free agent. If he blossoms from there, then great.”