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Case Keenum and the Broncos offense were melting in the afternoon heat. The journeyman quarterback couldn't muster much more than four-yard passes on 3rd-and-5, and he killed the Broncos' lone scoring drive with an interception near the goal line.

The Broncos defense in this Week 2 matchup against the Raiders was on the field for more than 20 first-half minutes in the near-100-degree heat, and it showed. Oakland marched up and down the field, taking a 12-0 lead that would have been far worse if not for some unforced errors.

Turnovers. Three-and-outs. A stout defense buckling under the strain. The Broncos suffered through it all for two years. That's why they handed Keenum a two-year, $36 million contract in March: to make it stop. But he wasn't getting the job done Sunday.

Instead, it was time for a little old-fashioned thunder and lightning. The Broncos unleashed their secret weapon: the unlikely backfield duo of rookies Phillip Lindsay and Royce Freeman.

Lindsay is a 5'8", 190-pound undrafted rookie from Colorado. Denver selected the 229-pound Freeman, who is Oregon's all-time leading rusher, in the third round this year. In a draft full of Saquon Barkley types, Freeman was an afterthought and Lindsay was barely a thought at all. But after two weeks, they've emerged as the NFL's hottest new backfield tandem.

Lindsay is now third in the NFL with 178 rushing yards, trailing only Matt Breida of the 49ers and Joe Mixon of the Bengals. He has also added 35 receiving yards and a touchdown. Freeman has rushed 23 times for 99 yards and had a critical touchdown Sunday.

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Paradoxically, the smaller Lindsay provided the thunder when the Broncos needed it Sunday, first on a 53-yard run in the second quarter (which Keenum's interception rendered irrelevant) and then on a series of rugged between-the-tackles runs in the second half. The burlier Freeman called forth the lightning on a 14-yard sweep before hammering home a one-yard touchdown that finally got the Broncos on the board.

There's clearly more to this one-two rookie punch than the old Mr. Inside/Mr. Outside dichotomy. Lindsay lines up everywhere from wide receiver to Wildcat quarterback, but he also grinds between the tackles and can pass-protect. Freeman was an accomplished receiver and pass protector when not carrying the load for the Ducks, and his 4.54-second 40-yard-dash speed makes him dangerous on the perimeter.

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That versatility makes Denver hard to scheme against, as opponents must be ready for anything with either (or both) of them on the field. They balance the Broncos offense and give Keenum better down-and-distance opportunities. On Sunday, they gave the defense a chance to hydrate. With the ground game clicking in the second half, the Broncos controlled the clock for nearly 18 minutes, and the Raiders defense ran out of gas in a 20-19 defeat.

That Lindsay and Freeman have emerged as two of the most productive rookies through Week 2 was far from preordained. The former has emerged as an unlikely star of this rookie class. In fact, it's a miracle that he even had the chance to play college football, let alone reach the NFL.

The diminutive runner suffered a catastrophic knee injury early during his senior season of high school. His family couldn't afford quality therapy after the surgery, and Lindsay developed so much scar tissue that he could barely bend or straighten his leg.

"My father would lay me on my back and my uncle would push my knee back to try to pop it to break the scar tissue," he told Bleacher Report before the draft. "Man, that was so painful."

The excruciating home remedies eventually gave way to more structured physical therapy. "I went from not thinking I would ever be able to play to being ready for my first college practice," Lindsay said.

Lindsay went on to gain 4,859 scrimmage yards and score 39 touchdowns for Colorado, earning a reputation as one of the team's toughest players. But in a star-studded running back draft, teams overlooked a pint-sized all-purpose back with an injury history from a down-on-its-luck program.

In the early rounds of the draft, teams also overlooked Freeman, who rushed for 3,201 yards and scored 38 total touchdowns in his first two collegiate seasons before nagging injuries and a scheme change caused his production to dip. Freeman played through a shoulder injury to rush for 1,475 yards and 16 touchdowns as a senior, breaking Oregon's career rushing record, only to draw criticism for choosing not to risk further injury by sitting out the Las Vegas Bowl.

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Freeman's NFL stock fell because he was overworked. Then his reputation took a hit because he didn't want to risk further overworking himself. That's the NFL draft process in a nutshell. He slipped under the radar and landed with the Broncos, a team which had not fielded a competent offense since the day Peyton Manning retired and was placing its trust in a 30-year-old journeyman QB coming off a career year.

The Broncos didn't sign Keenum to be Manning or John Elway. They just needed to get off the Trevor Siemian/Paxton Lynch/Brock Osweiler merry-go-round and were willing to pay a premium to do it. They needed Keenum to be a competent, professional game manager who wouldn't get in the defense's way.

Keenum is a clear upgrade over Siemian, Lynch and Osweiler, but that's faint praise. He threw three interceptions (and three touchdowns) in the narrow Week 1 victory over the Seahawks before leading the Broncos offense nowhere for a half on Sunday. Like most journeymen, Keenum is at his best when he's asked to do the least. He needs an effective running game and needs his receivers to rack up yards after the catch to be more than a caretaker under center.

Then again, even the best quarterback in Broncos history needed help from his running back.

Lindsay wears No. 30, which is Terrell Davis' old jersey number. The resemblance is so striking that studio announcers jokingly claimed Lindsay was Davis when narrating highlights of his Week 1 touchdown. The vertically challenged runner with the quick cuts and bruising style, the come-from-nowhere backstory of overcoming health issues; Lindsay has more than a little bit of Davis in him.

So does Freeman. Watch him patiently set up blocks on the perimeter before knifing upfield and you may flash back to the late 1990s, when Elway led the Broncos to a pair of Super Bowl victories by letting Davis do the bulk of the dirty work.

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These Broncos are not those Broncos. Keenum on his best day is barely half of Elway. It's too early to place the Lindsay-Freeman combination in the same category as Davis or his successors from the days when any running back who donned a Broncos uniform rushed for 1,000 yards.

But these Broncos are 2-0. For all of his faults, Keenum has helped to manufacture a pair of close wins. This team has many more paths to victory than hoping for strip-sacks and pick-sixes. Defense alone hasn't gotten the Broncos anywhere over the past two years, but running and defense can get a team mighty far, even if the quarterback doesn't quite live up to his contract.

Thanks to a pair of bargain-bin rookie running backs who have the potential to be special, the Broncos are relevant again.