Now he gets Dale Earnhardt Jr. and the circus that comes with him.
From family members to friends to perfect strangers, Mears can't go anywhere without being asked what it's like to work under the same roof as NASCAR's most popular driver.
"That is the question," Mears said last week during testing at Daytona International Speedway. "I'm kind of used to being around that with Jimmie and Jeff. But obviously Junior is the biggest, most popular guy out there.
"I'm going to do like I normally do except there'll be more cameras and people around."
Mears doesn't mind the cameras. He'd just like them to occasionally be on him instead of everybody else, which seldom happened a year ago with Johnson and Gordon finishing first and second in points and combining for 16 wins.
And when they weren't on Johnson and Gordon, they were on Busch, either for making the championship chase, for his job search after it was announced he would be replaced by Earnhardt or for something controversial he said or did.
"We want to do well and I want to show that I'm a driver that is worth being a part of this organization," Mears said.
Crew chief Alan Gustafson, who inherited Mears after Busch left for Joe Gibbs Racing this season, agreed.
"There's a big demand, you know, for Jeff Gordon and Jimmie Johnson and Dale Jr., which is great," he said. "I completely understand that. But it doesn't change anything that I do. I still want to win. I still want to compete. I still want to be the best."
Mears believes Earnhardt will help him and Gustafson achieve their goals and make the shop closer to what Johnson and Gordon have in the adjacent building at Hendrick's Concord, N.C., facility.
Throughout last season that ended with Johnson capturing his second consecutive title, the big story was about how well everybody in that shop worked together, how close Johnson and Gordon were as friends.
Nobody ever said that about Busch and Mears.
"Already the communication between [Earnhardt] and I versus myself and Kyle, for whatever reason, is better right out of the gate," Mears said. "That is going to help bring the 88 and 5 team closer together instead of somewhat separated in the same shop."
Earnhardt already is doing what he can to make that happen. He flew to testing last week to visit with Mears, Johnson and Gordon when he wasn't scheduled to be there until this week.
"I've known Jimmie for a longer period of time, and I've known Jeff even longer than that, but I never really spent time around them away from the racetrack," Earnhardt said. "I know how they are as race car drivers and what their work ethic is.
"But me and Casey will probably do more goofing off together. He's serious at the track and wants to do good, but we will spend time together where I might not do that so much with Jimmie and Jeff."
Mears' best explanation for why he and Busch never became close or why their teams didn't communicate as well as those of Johnson and Gordon goes back to the evolution of the shops.
"The 24 [Gordon] team was in a shop on its own, and when the 48 came in they basically made another 24 team and kind of went on," he said. "So it was easy to develop a system that worked for both cars.
"The 5 [Busch] and 25 [Mears] were two separate shops, already established doing totally different things and they were thrown together. It takes years to weed all of that out. It's been a slow process from what I understand."
The process was slowed more at the beginning of last season when Mears moved over from Chip Ganassi Racing to replace Brian Vickers, who went to Team Red Bull. A new team, with Darian Grubb taking over as crew chief only a few weeks before the opener at Daytona, had to be assembled.
Eleven weeks into the season, Mears had finished 20th or worse nine times and was 35th in points. People began to question his ability.
Then the turnaround began. Mears collected his first career Cup win, the Coca-Cola 600 at Lowe's Motor Speedway, and followed that with finishes of 13th, fourth and fourth to climb to 19th in points.
Already the communication between [Earnhardt] and I versus myself and Kyle, for whatever reason, is better right out of the gate. That is going to help bring the 88 and 5 team closer together instead of somewhat separated in the same shop.
-- Casey Mears
He ran off four consecutive top-10s when the Chase began to get to 14th. He finished 15th, posting a career-high five top-5s and 10 top-10s.
He then inherited basically the same team that helped Busch finish fifth in points because Earnhardt brought longtime crew chief Tony Eury Jr. and several other Dale Earnhardt Inc. crew members over to form the No. 88 team.
"Obviously, the success they've had the last few years we want to back that up," Mears said. "So there's definitely some pressure there. But at the same time it takes some of the pressure off that everybody is so focused on [my teammates] and we can just focus on our program and do the best we can."
This could be the breakout year many have anticipated from Mears. All the pieces are in place, and the chemistry he has established with Earnhardt can only help.
"If I can do anything to help out the 88 and vice versa, that can only make us stronger," Mears said. "Some of the stuff they learned during the offseason has already helped us. The Hendrick Motorsports goal is to have the 24-48 team continue the success they've had, and have the 88 and 5 step up to that caliber."
Gustafson likes what he's seen thus far. In some ways, he believes the team could be stronger with Mears.
"Kyle was young and had to go through some situations that arguably he handled wrong or not necessarily the right way in some people's eyes," he said. "I'm not judging him. Casey's a little more mature. He's seen a few more things, been through a few more experiences and is in a little better situation to handle them.
"Each driver has his own little idiosyncrasies. But some of the off-the-track stuff ... Casey's demeanor and experience may help him a little bit."
Mears definitely will have the best equipment of his career. He steps into a car that had 11 top-5s and 20 top-10s a year ago, into a team that was strong enough to contend for a title were it not for misfortune in the Chase.
"We can definitely make the Chase this year," Mears said. "We can win races. You know, we can contend to win the championship if we make it inside the Chase. We got to take it a step at a time, get through these first couple races and just kind of feel everything out.
"Obviously our goals are high this year. I feel like we definitely need to make the Chase, and then we'll go from there."
Whether that solves the identity crisis remains to be seen.
"Right now there's so many good things going for us," Mears said. "The fact that [Earnhardt's] coming in is definitely going to be a positive as well. You know, I mean, it never looks good if somebody's running way better than you are all the time on the same team. That's a given. That's an obvious.
"Right now, I just don't see that happening all year. Right now we're focused on running well."
David Newton covers NASCAR for ESPN.com. He can be reached at email@example.com.