INDIANAPOLIS - The offensive linemen were the first position group to work out and run the 40-yard dash at the NFL Scouting Combine on Friday, but the real show began later in the afternoon when the running backs took the field.

The consensus top four backs available – Leonard Fournette, Dalvin Cook, Christian McCaffrey and Alvin Kamara all took part in the workouts.

The big story early was Fournette's low 28.5-inch vertical jump – only two running backs in the last four combines posted worse vertical jumps: Matt Dayes (2017, 28 inches) and Kenny Hilliard (2015, 27 inches). Some worried that unimpressive leap would translate into a slow 40-yard dash time, since the vertical is a measurement of explosiveness. But Fournette posted 4.51 seconds in the 40 at 6-foot, 240 pounds, which is impressive.

Cook came in with an official time of 4.49 seconds, which is a good time for him, given his production at Florida State, his suddenness, and the fact that he put up 22 reps on the bench press, one of the top numbers for the position.

Stanford's do-it-all back, Christian McCaffrey, clocked in at 4.48. He was also impressive in the vertical (37.5) and broad jump (10-1).

Kamara was tops among all backs in the vertical (39.5) and broad jump (10-11), but his 40 time of 4.56 seconds was the 14th fastest among the backs.

North Carolina's T.J. Logan clocked the fastest 40 time among running backs with a 4.37.

• Tim Twentyman

BLOCKING PROWESS

Wide receivers can be divas at times. Some can even shy away from contact, especially when it comes to blocking in the run game. 

That won't be an issue for Western Michigan star Corey Davis, who is projected to be one of the first receivers off the board next month.

At 6-foot-3 and 215 pounds, Davis' game is predicated on both speed and physicality. When it comes to blocking downfield in the run game, he's more than willing.

"It's kind of a receivers only time and only chance to hit someone," Davis said of blocking at the Combine. "I definitely take full advantage of it. Blocking has a lot to do with just want-to and effort. That's something that I've learned in college ... it's something I've adapted in my game and I love doing it."

Davis suffered a high ankle sprain and two torn ligaments that required surgery. He isn't doing on-field work here at the Combine, but says he'll be full go by mid-April, and plans to work out for teams then.

• Tim Twentyman

MAKING THE CUT

Mitch Trubisky of North Carolina already has met one standard that helps separate quarterback prospects.

Trubisky was measured at an even 6 foot 2, which is the minimum height standard for many teams that will take a quarterback high in the draft.

The Cleveland Browns are in the market for a quarterback, and they have the first and 12th picks in the first round. They are unlikely to take a quarterback with the first pick, but head coach Hue Jackson answered succinctly when asked earlier in the week about the minimum height for a quarterback.

"6-2," Jackson replied succinctly, and with a small smile.

When asked to elaborate, Jackson repeated with a smile: "6-2."

Trubisky didn't seem fazed about the speculation over his height when in his media interview Thursday afternoon. He never gave any thought to how tall he'd be measured.

"No ... not at all," Trubisky said. "I know how tall I am. I knew I was going to measure that tall. I could have came out early and told everyone I was going to measure that. I just let it come out on measure day.

"It is what it is. It isn't going to affect me in any way."

-* Mike O'Hara*

PICKING BONO'S BRAIN

Quarterback Cooper Rush might be the only player from Central Michigan University at the Combine, but the resources available to him helped prepare him for the moment. 

His head coach in college, John Bonamego, has 16 years of NFL coaching experience, most recently as special teams coordinator of the Lions (2013-2014).

"He's given me tons of pointers coming into this," Rush said. "He's come to (the Combine) for about 16 years, so he's given me countless pointers and has been really supportive throughout the whole process. Anything I need, I ask … he's been really helpful."

What's the best advice Bonamego gave him?

"Just kind of own it," Rush said. "Just be yourself, own who you are. That's usually what works best with people. And try to enjoy the process."

-* Lindsay Selengowski*

GOING FAST

Throw on the film of Washington receiver John Ross and the first thing that stands out is his blazing speed.

He caught 81 passes for 1,150 yards and 17 touchdowns this past season and had 23 touchdowns in just 112 touches over his college career.

Ross says he's been running in the 4.2's in the 40-yard dash leading up to the Combine and hopes to run a sub-4.3 seconds when he hits the field Saturday.

The record low at the Combine belongs to running back Chris Johnson with a 4.24 in 2008.

-* Tim Twentyman*

QUOTE OF THE DAY

Ashland TE Adam Shaheen when asked how he put on more than 80 pounds (195 to 277) when he switched from basketball to football:

"A lot of Chipotle burritos."