Who was that?!? Unheralded ballers who made difference in Week 15

Rookie running back Jaylen Samuels rushed for 142 yards against the Patriots. Shelley Lipton/Icon Sportswire

We all know the NFL stars who generate SportsCenter highlights on a regular basis. Every week, though, some performances make us say, "Who was that?"

It could be the undrafted rookie receiver who catches a long touchdown pass, the backup quarterback who piles up stats or the journeyman linebacker who seals a victory with a big play.

This is for them.

Take a look at Week 15's unheralded ballers, starting with two rookie backup running backs who are taking full advantage of their opportunities and a backup QB who helped play spoiler in knocking off a division opponent.

Jaylen Samuels, RB, Pittsburgh Steelers

19 carries, 142 yards; two catches for 30 yards in 17-10 win over Patriots

Why it matters: The Steelers either have an embarrassment of riches at running back, or the perfect scheme to make everyone look like Le'Veon Bell, or both. Samuels has been the lead back with James Conner out with an injury, and he allowed the Steelers to control the tempo of the game. Samuels, a fifth-round pick out of NC State, is a hybrid tight end/H-back who is turning heads as a running back.

Kalen Ballage, RB, Miami Dolphins

12 carries for 123 yards, including 75-yard touchdown, in 41-17 loss to Vikings

Why it matters: With Frank Gore expected to be out for the season, Ballage will see a large portion of the reliable veteran's rushing workload. Gore and the Dolphins coaching staff love Ballage's potential and work ethic. Ballage, a fourth-round pick out of Arizona State, had just eight carries for 11 yards coming into this game -- but now he'll get a much bigger chance to show what goods he has.

Nick Mullens, QB, San Francisco 49ers

20-of-29, 275 yards, one touchdown, no interceptions in 26-23 OT win over Seahawks

Why it matters: The 49ers had to take joy in making Seattle's path to the playoffs just a little bit more difficult. Mullens showed strong command, took care of the football and made timely, clutch throws in maybe their best victory over the season. Jimmy Garoppolo is the 49ers' franchise QB, but Mullens is showing that he's certainly a top-tier backup, and he could eventually have some trade value if someone thinks he could be more than that.

Avonte Maddox and Corey Graham, DBs, Philadelphia Eagles

Both had interceptions in 30-23 win over Rams

Why it matters: The Eagles' depleted secondary faced an extremely difficult challenge headed into Los Angeles, but this unit stepped up just as much as backup quarterback Nick Foles. Maddox, a rookie safety, moved to outside cornerback in a pinch Sunday, and his interception prevented the Rams from getting points on a promising drive. Graham took advantage of a poor Jared Goff decision, intercepting a short pass that looked like it slipped out of the Rams quarterback's hand. That turnover set up the Eagles' final touchdown -- the difference-maker in the win. The Eagles will need continued contributions from their backup defensive backs if they hope to continue their improbable playoff push.

Chris Hubbard and Greg Robinson, OTs, Cleveland Browns

Allowed Von Miller and Bradley Chubb one sack between them Saturday night in 17-16 win over Broncos

Why it matters: The Broncos still had plenty to play for and had arguably the NFL's best pass-rush duo in Miller and Chubb (25.5 sacks combined coming into the game) taking aim at their rookie quarterback, Baker Mayfield. Cleveland offensive tackles Hubbard and Robinson had maybe their best games of the season, keeping Mayfield mostly clean.

ESPN NFL Nation reporter Pat McManamon contributed to this story.