With NASCAR's season only a month away, a few drivers are still adjusting to new teams and several crew chiefs are adjusting to new drivers.
Edwards, 35, is among the series' premier drivers, with 23 career wins, but a Cup championship has eluded him. Edwards came close in 2011 when he tied for first in points with Tony Stewart, but Stewart won the title because he had more wins that year.
Gibbs, the team owned by Hall of Fame NFL coach Joe Gibbs, also made big changes in its crew chief lineup after the team scored only two wins in 2014, one by Hamlin and one by Busch.
Crew chief Darian Grubb shifted to Edwards from Hamlin, Dave Rogers moved to Hamlin from Busch and Adam Stevens was promoted to take over Busch's car. Jason Ratcliff remains Kenseth's crew chief.
Coincidentally, Grubb was Stewart's crew chief when Stewart edged Edwards for the title in 2011.
In response to Edwards' departure, Roush Fenway gave Trevor Bayne a full-time Cup ride. Bayne, 23, won the Daytona 500 at age 20 in 2011 with a different team but since then mostly had raced in NASCAR's second-tier series.
That second-level series, formerly called the Nationwide Series, this year becomes the NASCAR Xfinity Series because of NASCAR's new naming-rights pact with Comcast Corp.'s Xfinity division.
Sam Hornish Jr., another driver who was racing in the second-tier series after a stint in the Cup series, likewise is returning to NASCAR's top level. Hornish will drive for Richard Petty Motorsports, replacing Marcos Ambrose, who returned to his native Australia.
After Hornish won the Indianapolis 500 and three IndyCar series titles, he shifted in 2007 to stock-car racing, where he's often struggled. But perseverance paid off for the 35-year-old native of Defiance, Ohio, who will now drive Petty's No. 9 Ford in the Cup series.
Brian Vickers, meanwhile, will miss the start of the Cup season after having corrective heart surgery. Vickers drives the No. 55 Toyota in the series for Michael Waltrip Racing.
Vickers, 31, initially had an artificial patch inserted to fix a hole in his heart in 2010 that also involved blood-clotting problems, and the latest surgery was to repair the patch. No timetable has been given for his return and a replacement driver hasn't yet been named.
The crew chief change that's likely to get the most attention involves the sport's most popular driver, Dale Earnhardt Jr., the defending Daytona 500 winner who drives for Hendrick Motorsports.
Earnhardt had a banner year in 2014, winning four races overall, with crew chief Steve Letarte. But Letarte left to be a TV analyst with NBC Sports and Hendrick named Greg Ives to replace him. Ives is a former race engineer for Earnhardt teammate Jimmie Johnson, the six-time Cup champion.
One thing hasn't changed in the Cup series: Johnson remains a favorite to join Petty and the late Dale Earnhardt Sr. as the only drivers to win seven titles, even though Johnson last year finished an atypical 11th in the standings.
In the Xfinity Series, Elliott Sadler — who finished third in the second-tier series' standings last year — moves to Roush Fenway from Gibbs, while Darrell Wallace Jr. steps up to the Xfinity Series with Roush Fenway.
Wallace, 21, had been racing in NASCAR's Camping World Truck Series. When he won his first truck race in 2013, he became the first African American driver to win in one of NASCAR's three national series in nearly 50 years. Wallace won four more truck races last season.
And under NASCAR's new television rights deal, NBC Sports will carry broadcasts of the second half of the Cup season, including the 10-race Chase for the Cup title playoff, replacing ESPN. Fox carries the first half.
Follow Jim Peltz on Twitter @PeltzLATimes