But he'd been around enough basketball outside of his alma mater to know that keeping up with the times is never a bad thing.
The famed system relies heavily on movement, precision passing, back-cuts and — above all — patience. It can make for a slower game and capitalizes on opponents who either get lulled to sleep or are caught during lapses in judgment.
While keeping the principles of the Princeton offense alive, a few of those modifications that Johnson instituted helped the Tigers put together a 20-minute stretch on Tuesday night that saved their season and kept their hopes of the program's first NCAA tournament berth since 2004 alive.
After trailing 23-19 at the break in their regular season finale at Penn — a game Princeton had to win to claim a share of the Ivy League title and force a one-game playoff with Harvard this Saturday — Johnson's club erupted for 51 points after the half en route to a 70-58 win.
"Most people look at (the 51 points) as a Princeton score for a whole game," Johnson joked afterwards. "We can play fast and can score.
"I don't want to lead people astray. We're not the (UNLV) Runnin' Rebels, we're not the (North) Carolina fast break, but we're also not walking the ball up. We have talent, and we have talent that can score. With that in mind, we're just letting them play a bit more free."
After the Tigers went 6-23 in Johnson's first season, they improved to 13-14 in 2008-09, 22-9 a year ago and now will enter Saturday afternoon's third meeting with the Crimson at 24-6 overall and 12-2 in the Ivy.
Johnson played for both Pete Carril and Bill Carmody in his four seasons as a Princeton standout, graduated in 1997 and then went overseas for the next seven seasons, picking up little nuances along the way in a seven-year professional career.
"The shot clock over there, it's 24 seconds just like it is in the NBA," he said. "Just to be honest, there's a lot more scoring. As pros, the guys are a lot more aggressive individually, and you start to appreciate it. If a guy can get you 25 points coming off of a ball screen, there's nothing wrong with putting that into your offense."
The finishing touches for Johnson's specific coaching style were added by working as an assistant at Georgetown from 2004-07 under John Thompson III, a Princeton assistant during Johnson's days as a Tiger.
"I liked how he gave the guys at the Big East level, guys with NBA talent, a style of play where they could express themselves but also out-think the guys they were playing," he explained. "Guys like Jeff Green, DaJuan Summers, Greg Monroe."
The Tigers certainly appeared to be playing with a good amount of freedom in Tuesday's second stanza, mixing in patient possessions that ended in timely 3-point makes with a bevy of one-on-one attacks at the rim. The latter effort was led by 6-foot-8 senior swingman Kareem Maddox who scored 21 of his game-high 23 points after the intermission by being unrelenting against Penn's vulnerable interior.
It marked the eighth time this season in which Princeton has scored in the 70s. The Tigers have reached the 80s on four occasions.
"We've had some decent scoring games," Johnson said. "And we don't mind that at all."
One more of those could be just what Princeton needs to go dancing.
The Ivy is the only Division-I league whose automatic NCAA tournament bid is not handed out at the end of a conference tournament. The tie forced by Tuesday's Princeton win at Penn creates Saturday's winner-take-all duel to be held at Yale.
"I don't want to hurt anyone's feelings, but I think it's the best way to do it in a single-bid league," Johnson said. "We would love to win that game and move on, but before that, I'll say it's the best way to go about it."
Princeton and Harvard split the first two meetings this season, with each winning on its home floor.
Tommy Amaker has the Crimson on the up and up, not just threatening for their first NCAA bid since — get ready for this — 1946, but with a big-time recruiting class coming in next season, he'll be near the top of the league for years.
With Johnson having restored Princeton's winning ways, the rivalry appears to be on its way to the next level.
Before thinking that far ahead, Johnson is too concerned about whether this season will go down in the books as, in his words, either terrific or great.
"We've had a terrific season, no doubt — We won an Ivy League championship, won a lot of games, won all of our games at home, 20 games in back-to-back seasons," Johnson said. "The great season would be winning the Ivy League championship and moving onto the NCAA tournament."