Like a Peyton Manning-led offense, the NFL is constantly in motion.
Tweaks here, wholesale alterations there … the league is never quite the same from year to year.
A look at some of the changes for the 2015 season:
The NFL tinkers with its rules virtually every off-season. Some adjustments are more obvious than others, including a particularly noticeable change to the kicking game this fall.
The extra-point attempt will now be snapped from the 15-yard line, slightly ramping up the degree of difficulty for what has become a "gimme" play. Two-point conversions will remain at the two-yard line. Defenses will be allowed to return a blocked kick, interception or fumble on PATs or conversion attempts for two points.
More subtle are some of the changes to the unnecessary-roughness rule. As has been the case, such penalties result in a 15-yard penalty and may warrant discipline.
•This season, defenseless player protections will extend to the intended receiver of a pass following an interception or potential interception. So no more free shots to the head or neck area of a receiver who is clearly tracking the ball and in a defenseless position.
•The ban on illegal "peel-back" blocks now extends to all offensive players. So when approaching an opponent from the side, a blocker must get his shoulder across the front of his opponent's body to legally block him below the waist.
•All chop blocks involving a back are eliminated to give defenders additional protection from low blocks.
•The ban on pushing teammates into the offensive formation is extended to punt plays.
Extra medical eyes
The independent ATC spotters (certified athletic trainers) watching from the press box are now allowed to notify officials to stop a game if a player shows obvious signs of disorientation or is clearly unstable. In those cases, the game will be stopped immediately and the player in question will be removed from the game for further medical examination on the sideline.
The San Francisco 49ers will travel the most miles during the 2015 regular season, logging 27,912. The NFC West travels the most combined miles (90,990) of all divisions. Considering a trip around the circumference of the Earth is about 25,000 miles, three teams — the 49ers, Miami Dolphins and Oakland Raiders — will fly at least the equivalent of that.
Philadelphia travels the fewest miles, a relatively paltry 6,890.
95th: The NFL was founded in Canton, Ohio, on Aug. 20, 1920.
90th: Tim Mara and Billy Gibson were awarded a new NFL franchise for a fee of $500 — the New York Giants.
75th: In the biggest blowout in league history, Chicago beat Washington, 73-0, for the NFL championship.
60th: The Baltimore Colts made a long-distance call to sign a young free-agent quarterback, Johnny Unitas. It wasn't free — the call cost 80 cents.
45th: The AFL and NFL merged into one league.
45th: The Super Bowl trophy was renamed the Vince Lombardi Trophy.
35th: The NFL draft was televised for the first time, by ESPN.
25th: The bye week was introduced and the 16-game schedule was played over 17 weeks.
10th: NFL Network began televising regular-season games.
5th: Team owners voted to amend postseason overtime rules to a modified sudden-death format, guaranteeing at least one possession for each club (as long as the team that gets the ball first doesn't score a touchdown).
Milestones in making
•Denver quarterback Peyton Manning needs 2,148 yards passing to surpass Brett Favre's all-time career mark of 71,838.
•Manning needs 374 completions to pass Favre's 6,300 for the most in history.
•New Orleans quarterback Drew Brees needs 4,000 yards passing to join Manning (14) as the only players in league history with at least 10 such seasons.
•New England's Tom Brady needs eight touchdown passes to join Dan Marino, Favre and Manning as the only players with 400 touchdown passes.
•San Diego's Philip Rivers has led the league in average yards per pass three times. Once more, and he would join Steve Young (5) and Sid Luckman (7) as the only players to do that at least four times.
•Minnesota's Adrian Peterson needs 10 rushing touchdowns to join Emmitt Smith (eight) and LaDainian Tomlinson (nine) as the only players to rush for 10 in at least eight seasons.
•Houston's Arian Foster needs 1,864 yards rushing to pass Priest Holmes (8,172) for the most career yards by an undrafted player.
•Indianapolis receiver Andre Johnson needs 100 catches to become the first NFL player to reach that milestone six times. Same goes for New York Jets receiver Brandon Marshall, who likewise has done it five times.
•Detroit receiver Calvin Johnson needs one more 200-yard receiving game for a record sixth. He is currently tied with Lance Alworth in that category.
•Dallas' Jason Witten needs 57 receptions to join the retired Tony Gonzalez as the only tight ends with 1,000 career catches.
•San Diego's Antonio Gates needs one touchdown reception to join Gonzalez (111) as the only tight ends with 100 career scoring catches.
•Oakland's Charles Woodson has returned 11 interceptions for touchdowns in his career. Two more, and he would surpass Hall of Famer Rod Woodson (no relation) for the most all time.
•Chicago's Jared Allen has led the NFL in sacks twice in his career. Once more and he would become the first player to do that three times since sacks became an official statistic in 1982. (Players such as Deacon Jones were regularly sacking quarterbacks before the league had a name for that.)
•Oakland's Sebastian Janikowski needs five 50-yard field goals to surpass Jason Hanson (52) for the most in history.
Faces in new places
QB Sam Bradford, Philadelphia: The former No. 1 overall pick was traded to the Eagles after consecutive seasons were cut short by knee injuries.
CB Brandon Browner, New Orleans: Saints get a big-bodied corner who played integral roles for the last two Super Bowl champs, New England and Seattle.
RB Reggie Bush, San Francisco: Probable last stop for the well-traveled Heisman Trophy-winning tailback from USC. He wants to return punts.
DT Darnell Dockett, San Francisco: A longtime disruptive force on Arizona's defensive front moves north in the NFC West to join a rival.
QB Nick Foles, St. Louis: The Eagles got Bradford, and the Rams got Foles, who's eager to prove his one spectacular season in Philadelphia wasn't a fluke.
RB Frank Gore, Indianapolis: Gore, a 49ers fixture for a decade, thought hard about joining the Eagles but decided his Super Bowl odds were better with the Colts.
TE Jimmy Graham, Seattle: The Seahawks needed another red-zone target — see pivotal play in Super Bowl loss — and Graham gives them one of the best.
WR Andre Johnson, Indianapolis: Former Houston star decided with Gore, his college teammate at Miami, to join bitter AFC South rival and play for a ring.
WR Jeremy Maclin, Kansas City: A multipurpose threat in Philadelphia, Maclin joins a Chiefs team that got precious little from its receivers last season.
RB LeSean McCoy, Buffalo: Rex Ryan moved aggressively as new coach of the Bills, making a trade with the Eagles for McCoy, among the league's more elusive backs.
S Rahim Moore, Houston: Former UCLA standout Moore was Denver's second-round pick in John Elway's first draft as the team's top football executive.
RB DeMarco Murray, Philadelphia: Eagles think last year's rushing champion still has something left in the tank, even though he had about 400 touches for Dallas in 2014.
DT Haloti Ngata, Detroit: The Lions lost Ndamukong Suh and needed a presence in the middle. They were happy to land Ngata, who anchored Baltimore's defensive front for so long.
CB Darrelle Revis, New York Jets: Life has come full circle for Revis, who returns to the Jets after a lousy season in Tampa Bay and a Super Bowl season in New England.
DT Ndamukong Suh, Miami: The prize of free agency, Suh adds big-time punch to a Miami defensive front that already has good pass-rushing ends.
TE Julius Thomas, Jacksonville: A prime Peyton Manning target moves on from Denver and will help in the development of second-year quarterback Blake Bortles. That will have to wait at least until Week 4, however, now that Thomas has undergone surgery to repair ligament damage in his right hand.
C Max Unger, New Orleans: A key component (when healthy) on Seattle's offensive line, Unger wound up with the Saints as part of the Graham trade.
RB Shane Vereen, New York Giants: A Super Bowl standout for the Patriots, Vereen moves on to the Giants, where he'll be appreciated by Eli Manning.
QB Michael Vick, Pittsburgh: Vick, who spent last season with the Jets, moves on to his fourth team, this time as a backup to Ben Roethlisberger.
DT Vince Wilfork, Houston: For so long he was the mountain in the middle of the Patriots' defense. Now, he'll be shoulder to shoulder with J.J. Watt.