The Quarterbacks took the field in Indianapolis Saturday as the NFL Combine rolls on:

Sam Darnold opted not to throw at the NFL Scouting Combine for the same reason Lamar Jackson chose not to run. They felt they proved enough in college.

Jackson, however, knew he had to show off his arm. Saturday was the quarterbacks' turn for on-field workouts at Lucas Oil Stadium in Indianapolis, and Jackson, Josh Rosen, Josh Allen and Baker Mayfield took turns while Darnold watched.

"I don't need to show off my speed and show people I can make them miss," Jackson said. "I have to show off my arm because that's where they doubt me."

When speaking to the media the day before participating in drills, Jackson shot down rumors that some teams asked the 6-foot-2, 216-pound quarterback to work out as a wide receiver. "I'm strictly a quarterback," he repeated several times in response to questions along those lines.  

Jackson is one of two Heisman Trophy winners in this year's quarterbacks class -- Mayfield is the other -- after becoming the youngest player ever to win the award as a sophomore in 2016.  That year, the Louisville product set ACC records for the most rushing yards (1,571) and rushing touchdowns by a quarterback (21). He went on to finish his career with 4,132 yards and 50 scores on the ground. Through the air, Jackson completed 57 percent of his passes for 9,043 yards (238.0 per game) and 69 touchdowns to 27 interceptions.

So how did his arm look on Saturday?

"I think you saw he's still a work in progress," said NFL Network's Daniel Jeremiah, a former NFL scout. "Every couple throws you'd see the ball come out nice and the ball would have a nice pace on it. I thought, overall, [he was] much more comfortable. Everything was working in, working into the middle of the field. It's like that way on tape as well. When he has to drive the ball outside, he was a little bit up and down. I thought he tried to slow himself down a little bit and guide the ball, which cost him a little bit of pace. But overall it was an up and down day for Lamar, in my opinion."

Jeremiah added: "You've been taught your whole life you want completions – completions, completions, completions. … I think if there was some people looking for him to totally light it up, I don't know that he did that. I think some other people thought he would just completely fall on his face; he didn't do that, either. I thought it was just kind of a very middle of the road workout for Lamar. He's still got work to do, but the upside is so interesting."

Here are more notes from the NFL Network crew about how the other quarterback prospects fared on Saturday:

JOSH ROSEN, UCLA

"He had a worm burner early on in the workout on a slant route and then just kind of skipped it," Jeremiah said. "The thing I loved about it is he kind of laughed it off, and then after that, he got right into a rhythm and you saw the ball just kind of jumps out of his hand. He throws a little bit of a flat ball. We saw that on some of the deep balls a little later on in the workout, but everything is free and easy and smooth with Josh Rosen."

JOSH ALLEN, WYOMING

"Guys like Josh Allen, the ball just naturally comes off his hand with effortless velocity," said David Carr, a former No. 1 overall draft pick as well as an Eli Manning backup. "So that's kind of nice to see. It's as advertised. The accuracy stuff, 56 percent in college, is obviously well documented, but the kid can rip it when he gets out here and throws it. [He was] a little shaky with the first couple of throws, but that's to be expected. … It's just effortless. He gets back there, it doesn't even look like he's working hard and the ball just kind of flips out of his hands. So it's a good sign."

"With Josh on his film, about every seventh or eighth or ninth throw, you go, 'What was that?'" Mike Mayock said. "Just his feet aren't under his body, he's disconnected, and an ugly throw comes out. But when it's all synced up, the best-looking ball -- he's got the biggest arm I've seen since JaMarcus Russell."

BAKER MAYFIELD, OKLAHOMA

"A lot of depth in this quarterback class," Jeremiah said. "I thought it was a very solid day overall. Josh Allen stole the show, but you look at Baker Mayfield, what he did in that second group, he was outstanding."

"If you draft Baker Mayfield in the first round, you better set your system up around what he does well, as opposed to just saying we're a West Coast or we're down the field, or whatever you want to call it," Mayock said. "So I look at him and go, yeah, components of the West Coast system fit him well, but there have to be components of the RPO, play action, get him out in the run. He's an exciting talent, and I think an intelligent coach will know how to use him to the best of his ability."