There's a generation of Royals fans who have heard stories about that success, but seeing is believing, and it's hard for them to take the talk of a Kansas City team that was a dominant force seriously.
That forgettable segment of the franchise's history could soon be forgotten.
A franchise that hasn't even won 90 games since 1989 -- and has had a winning record only three times since then -- has reason to feel it's ready to return to the world of legitimate contenders. And while Brett now serves as vice president of baseball operations for the Royals, it is safe to say that he played a role in a pending resurgence when he assumed a coaching role for two months in the middle of last season.
It was late May, and a season that started out so well in the opening month was already slipping away. Kansas City went into the final days of May having lost 19 of 23 games, an offense that the front office felt was ready to be a factor had instead gone flat.
Brett and Pedro Grifol were brought in on May 30 as a two-headed hitting coach. Grifol was given the responsibility of working on the technical aspects. Brett was there to help with the mental aspects. Two months later, Brett returned to the front office, and the Royals were headed back in the right direction.
After finishing off an 8-20 month of May, Kansas City rebounded and actually made a run for a Wild Card berth, settling for a third-place finish in the American League Central and 86 wins, only the club's third winning record in 20 seasons and its most victories winning 92 games in 1989.
"George got them to understand who they were as a player," manager Ned Yost said.
Who the Royals were -- and who they are -- is pretty good, and when they click together, they have a chance to be real good.
"We developed a confidence," said designated hitter Billy Butler. "We knew every guy [in the lineup] could do the job. We didn't have to break the team out of a long losing streak by yourself. We could do it as a team."
The Royals did.
They had a winning record in every month last season except May, when their 8-20 record made them one of 31 teams in the past 30 years to stumble through the month of May with a winning percentage of .286 or worse. But they were one of only two of those 31 teams to finish the season with a winning record. The 1985 Oakland A's were 7-20 in May but rallied to win 88 games, finishing second in the AL West and then winning the division in '86.
"We had a good April [a year ago], but in May, we just quit hitting," Yost said. "A lot of that was the offense was pressing, trying to do too much. Each guy wanted to be the guy who changed things.
"You always look to see how a team is going to rebound from something like that."
In 2011, the Royals didn't rebound. They stumbled to a 9-18 June that year, which was the middle of a stretch in which they lost 33 of 46 games, and faded into oblivion.
The 2013 Royals did rebound.
There were two key tests of their resolve. They went into the All-Star break on a five-game losing streak, capped off by a sweep at Cleveland. When play resumed, Kansas City won 11 of its first 13 games, climbing back above .500 for good. The club also endured a seven-game losing streak in late August, but bounced back by winning five in a row.
"A big part of it is having confidence about what you can do," Yost said. "You know that when things get hard, you don't press, you just play your game, and that's what they did.
"You always hear me say something clicked. That's what clicked. They believed in themselves and the played hard. They reacted to situations, and they reacted well."
And that was in no small part a result of the two months Brett spent in uniform.
"George got them to understand who they were as players," Yost said. "He'd walk up to a player like Mike Moustakas and say, 'What's your name?' He'd say, 'Mike Moustakas.' George would say, 'That's right, Mike Moustakas. Now play like Mike Moustakas. You're not Barry Bonds.'"
Sounds so simple, but it is so hard to grasp.
Brett knows too well. A 13-time All-Star who won three batting titles, including in 1980 when he hit .390, Brett had moments of doubt in his rookie season. The late Charlie Lau challenged Brett, demanding the left-handed batter hit every ball between second base and third base.
And when Brett pulled a ball, he felt the wrath of Lau.
Then came the game of reckoning. On Aug. 6, 1977, Brett's fourth full season in the big leagues, the Royals trailed the Chicago White Sox, 3-1, in the bottom of the seventh. The first two hitters reached base, and as Brett began to walk to the plate to face lefty Dave Hamilton, Lau called him over.
"He told me Hamilton had trouble getting the ball in on left-handers," Brett remembered. "I stood way off the plate, and Charlie told me to move up a couple inches and put a good swing on a pitch on the inner half. The first pitch was right there, and I swung. I hit it over the fence.
"I remember circling the bases and then going into the dugout, seeing Charlie and telling him, 'I didn't try to hit it out. I didn't try to hit it out. I just tried to drive it.'"
Brett remembers a smile coming across Lau's face.
"He told me, 'You've got it, kid. It's not about trying to hit the ball out. It's about hitting the ball hard,'" Brett remembered. "And that's why I try to tell the guys, 'Don't feel like you have to do everything yourself. Trust your teammates.'"
A year ago, the Royals heard that message, loud and clear. The challenge is to remember it in the season ahead.