Who was that?!? Check out the NFL's Quarter 2 unheralded ballers

Mecole Hardman has 20 catches and four touchdowns for the Chiefs. Ed Zurga/AP Photo

We all know the NFL stars who fuel conversation on SportsCenter with weekly monster games, showing off their eye-popping highlight skills. But what about the performances that make us say, "Who was that?"

It could be the undrafted rookie who becomes his team’s leading receiver, the backup quarterback who leads his team to one or two upset road victories, or the journeyman defensive end who out of nowhere becomes the sack bogeyman.

This is for them.

Introducing the NFL’s Quarter 2 unheralded ballers, starting with another Kansas City speedster and an undrafted cornerback filling some big shoes.

Chiefs WR Mecole Hardman

20 catches for 374 yards, 4 TDs and a 18.7-yards-per-catch average

Why it matters: Tyreek Hill missed four games because of injury, and Hardman took excellent advantage of that opportunity immediately, becoming a feared big-play weapon. The rookie makes an elite Chiefs offense even more versatile and dangerous.

The second-round pick out of Georgia never had more than 35 catches or 543 yards in a season while in college, and he’s on pace to surpass both of those figures as an NFL rookie. Hardman's top speed of 21.74 mph on an 83-yard touchdown in Week 3 was among the top 10 in the league so far this season, according to NFL Next Gen Stats data.

Jaguars CB Tre Herndon

Two interceptions filling Jalen Ramsey’s former role

Why it matters: Herndon was picked on by opponents during Ramsey’s absence, but he’s used those challenges to make himself better. The 2018 undrafted free agent out of Vanderbilt was primarily a special-teams player until Ramsey’s back injury, and he maximized that opportunity to become a full-time starter after Ramsey was traded.

Herndon nearly had his first career interception against the Panthers on Oct. 6, then got on board with two picks of Sam Darnold on Sunday. That’s one way to earn respect.

Packers WRs Allen Lazard and Jake Kumerow

Combined for 18 catches for 268 yards in past three games

Why it matters: Forced into action because of Davante Adams’ Week 4 turf toe injury, Kumerow (a second-year undrafted player) and Lazard (an undrafted rookie) have stepped up to the plate big time, helping make the 7-1 Packers one of the NFC’s elite teams.

“I really am proud of the way that Jake has played and Allen has played,” quarterback Aaron Rodgers said.

Adams should return sooner than later, but the production of Kumerow and Lazard in a time of need could have a lasting impact on the Packers' offense.

Vikings RB Alexander Mattison

331 rushing yards, 4.9 yards per carry as Dalvin Cook’s backup

Why it matters: Mattison has more rushing yards than Joe Mixon and David Johnson so far this season, and the rookie hasn’t started a single game. Mattison’s main role is spelling Cook, and he’s made the most of those opportunities.

The third-round pick out of Boise State already looks like a strong find for Minnesota. The Vikings' smashmouth offense has two capable backs.

49ers CB Emmanuel Moseley

Filled in for an injured Ahkello Witherspoon with strong pass defense and an interception

Why it matters: The 49ers made a big statement to those who doubted whether they were a true NFC contender by beating the Panthers by 38, and a big part of that was a strong defensive performance featuring unheralded players such as Moseley.

The 2018 undrafted free agent was promoted off the practice squad late last season, then was injured. He made the team from Week 1 this season, and emerged as a real player holding down the fort for Witherspoon. The unbeaten 49ers might have found something in Moseley.

ESPN NFL Nation reporters Rob Demovsky, Mike DiRocco and Nick Wagoner contributed to this story.