NFL Week 1: 5 Things We Learned from Opening Weekend

The first week of regular-season NFL action is in the books, and it has already delivered surprising upsets, such as the Buffalo Bills taking down the Indianapolis Colts; emerging stars, like Marcus Mariota; intense interdivision competition, looking at you St. Louis Rams; and worrisome reflections (don't panic yet, Houston!) as advertised.

For some, morale is already low, with a few teams faced with injuries to crucial players. Others were delivered victory by new additions and are prematurely projecting success.

Yes, with new coaches and players on multiple teams, college stars turning pro and previous unknowns making a name for themselves, it can get a little confusing. But fear not!

Here's what it all boils down to.

Super Mariota Proves He's Pro-Ready

Brian Blanco/Associated Press

In the highly anticipated battle between this year's first and second overall draft picks, Marcus Mariota of the Tennessee Titans thoroughly bested Jameis Winston and the Tampa Bay Buccaneers.

In three quarters of play, Mariota completed 13 of his 16 passes for 209 yards and a passer rating of 158.3. With his tremendous work done, he spent the fourth quarter watching backup Zach Mettenberger guide the Titans to a 42-14 victory. 

Along with instilling hope in the hearts of Titans fans previously demoralized by 2014's 2-14 season, Mariota became linked to some pretty elite company, too. 

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Titans' QB Marcus Mariota joined Hall of Famer Fran Tarkenton as only rookies in NFL history to throw 4 touchdown passes on opening weekend.

— Adam Schefter (@AdamSchefter) September 14, 2015

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For now, with losses by the Indianapolis Colts, Houston Texans and Jacksonville Jaguars, Mariota and the Titans sit atop the AFC South. While that may not become a permanent arrangement, their strength of schedule, which according to CBSSports.com's John Breech is seventh-easiest in the league (.435 2014 opponent winning percentage), certainly lends itself to an optimistic outlook. 

As for Winston, he isn't in such poor company either.

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Jameis Winston: 1st player to throw a "pick-6" on his first NFL pass since Brett Favre for the Falcons in 1991 (via @eliassports)

— ESPN Stats & Info (@ESPNStatsInfo) September 13, 2015"

Beware the Buffalo Bills (and the Rest of the AFC East)

Bill Wippert/Associated Press

After a full day of football on Sunday, all four teams in the AFC East had begun their seasons 1-0. 

Perhaps the unlikeliest of the victories was the Buffalo Bill's 27-14 triumph over the presumed Super Bowl-contending Indianapolis Colts. Or was it?

Boasting a traditionally stout defense headlined by defensive end Mario Williams and an offense featuring emerging you wide receiver Sammy Watkins and former Pro Bowl running back LeSean McCoy, the Bills were just a committed coach and solid starting quarterback away from being great.

In head coach Rex Ryan and QB Tyrod Taylor, both of whom made their regular-season debuts with the team Sunday, it seems they may have found those missing pieces. 

Getting past the reigning Super Bowl champion New England Patriots will likely be no any easier than it has been in previous seasons, and the emerging Miami Dolphins and New York Jets might make for a tough fight, but the Bills have good reason to be optimistic.

"We have a chance to be very special," said Taylor in an official press conference following the game. "Just looking forward to continuing to keep getting better."

With Chargers, Chiefs on the Rise, the Denver Broncos Are on a Tight Rein

Joe Mahoney/Associated Press

The Denver Broncos will have no time to stop and enjoy their victory over the Baltimore Ravens.

On Thursday, Peyton Manning and Co., now under the guidance of Gary Kubiak, will take on the steadily improving Kansas City Chiefs. 

As displayed in their 27-20 victory over the Houston Texans, the Chiefs' sometimes suspect passing offense is finally performing at a high level.

Running back Jamaal Charles and tight end Travis Kelce have continued the level excellence they displayed a season ago, while free-agency addition Jeremy Maclin is already fitting in at receiver. QB Alex Smith, a consistent, positive presence for the offense, should thrive with these weapons and the support of head coach Andy Reid.

Defeating the Chiefs on Thursday will only be part of the battle for the Broncos, however. Kansas City will likely be in hot pursuit for the entirety of the season. So, too, will the San Diego Chargers.

With 15th overall 2015 NFL draft selection Melvin Gordon, the Chargers may have found the long-term answer to one of their glaring offensive needs. Meanwhile, Philip Rivers, who was re-signed this summer to a four-year, $84 million extension, proved in the 33-28 victory over the Detroit Lions that he is still more than capable of winning a game with his arm.

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Philip Rivers: 404 passing yards, sets record for most by a Chargers QB in a season opener

— ESPN Stats & Info (@ESPNStatsInfo) September 13, 2015

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The Broncos aren't the only ones with legitimate interdivision threats either. Despite the decline of the San Francisco 49ers, the Seattle Seahawks still have no margin for error. Their 34-31 overtime loss to their NFC West rival St. Louis Rams puts them one game back from the competitive Arizona Cardinals, who convincingly took down Drew Brees and the Saints 31-19.

Not All QB Debuts Are Created Equal

Chris O'Meara/Associated Press

A total of seven—yes, seven—quarterbacks made their starting debuts with new teams on Sunday, with rookie first-round selections Marcus Mariota and Jameis Winston rounding out the statistical top and bottom of the week.

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Total QBR on Sunday Marcus Mariota 95.7 (highest so far this week) Jameis Winston 6.7 (lowest so far this week)

— ESPN Stats & Info (@ESPNStatsInfo) September 14, 2015"

Winston, however, isn't the only player who might want a do-over for Sunday. Houston Texans QB Brian Hoyer completed just 18 of his 34 passes for 236 yards on his was to accumulating a touchdown pass, an interception and a lost fumble before being yanked in favor of backup Ryan Mallett with a final QBR of 12.3—not much better than Winston's.

Josh McCown's Cleveland Browns debut didn't even last a full drive before he was taken out of the game after head contact with New York Jets linebacker Demario Davis.

Former Philadelphia Eagle Nick Foles was a solid presence for the St. Louis Rams in their 34-31 OT victory over their division rival Seattle Seahawks, completing 18 of 27 passes for 297 yards with a touchdown on the ground and through the air. 

So was journeyman backup Ryan Fitzpatrick (15 of 24, 179 yards, two touchdowns, one pick), who started for the Jets in Geno Smith's absence. Buffalo Bill's Tyrod Taylor (14 of 19, 195 yards, one touchdown) was also impressive in his team's 27-14 victory over the Colts. 

Starting quarterback inconsistency is obviously a league-wide epidemic. While not too much stock should be put into Week 1 performances, those teams happy with their new signal-callers are more than likely on track for greater success than those who will soon begin their scramble for other answers.

The Pack Prevail Despite Big-Name Player Injuries; Panthers and Texans Struggle

Wesley Hitt/Getty Images

After a plague of training-camp and preseason injuries swept throughout the league, three teams in particular, the Green Bay Packers, the Carolina Panthers and the Houston Texans, entered the season without one of their marquee offensive players.

Unlike the other two squads, the Packers, who opened with a 31-23 win against the Chicago Bears without the services of receiver Jordy Nelson, found ways to pick up the slack. Thanks in large part to the excellent play of Aaron Rodgers, receivers Davante Adams, Randall Cobb and James Jones combined for a total of 148 yards through the air and three scores. 

While many wondered whether the loss of Nelson would have a negative impact on their shot at a deep playoff run, all signs at this point seem to indicate that won't be the case.

Meanwhile, Panthers receivers Jerricho Cotchery (45 yards) and Ted Ginn Jr. (54 yards), who dropped what likely would have been a touchdown in the first quarter, turned out to be largely inadequate replacements, despite a 20-9 victory over the Jacksonville Jaguars. 

Likewise, Houston, defeated 27-20 by the Kansas City Chiefs without the help of Arian Foster, only managed 93 yards rushing with three-man committee Alfred Blue, Chris Polk and Jonathan Grimes. They were unable to successfully run their traditional offense as a result.

But while Carolina will be forced to search for a substitute playmaker, CBSSports.com's Jason La Canfora has reported that Foster could return for the Texans as early as next week's contest against the Panthers.

Finally, after Sunday night's win over the New York Giants, the Dallas Cowboys will be without their offensive centerpiece, Dez Bryant, which should open the door for the Giants and Philadelphia Eagles in what could be a three-way race for the NFC East.

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After the win over the #Giants last night, the #Cowboys said WR Dez Bryant would be out 4-6 weeks with a broken bone in his foot.

— Ian Rapoport (@RapSheet) September 14, 2015"

All statistical data sourced from ESPN.go.com.