It was a topic raised because Johnson has been brought in to implement a high-pressing game built on energy and speed both on and off the ball.
At 35, the initial wisdom may have been that Leadbitter might struggle to find a natural role.
Johnson could not have been clearer in stating why that would not be the case and just a couple of days later, he had immediate evidence to back up his argument.
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Sunderland dismissed Burton Albion in a controlled, clinical display.
There was pace throughout the side and some ruthless counter-attacking, but it was built on the foundation of the dominance that both Leadbitter and Max Power enjoyed in the middle of the park.
"If you look at Grant's strengths, his vision, his ability, touch, tidy-up play, is top level," Johnson had explained.
"And I mean top level.
"I can understand that, sometimes he is almost too good which is why he can slow that forward pass down, and I can imagine that's what the external can see.
"He's fit, he's 35 but his lung capacity is very good.
"If a player is that good on the ball, then you look at someone like Tugay when he was at Blackburn, they may not be quick but they're always on time.
"That's an important factor.
"He's tough, he's good in 50-50's and he's the daddy in there that we'll need in certain games.
"He knows for my style and intensity he won't play every minute but he's done a fantastic job even when he's come on from the bench.
"If you look at MK Dons away in the Trophy, he came on at 1-0 to us but still very end-to-end, he came on and we must have had three sequences of 30+ passes that he dictated.
"It's about control on and off the ball, and he's an important factor in that.
"There'll be games where we go with pure energy, and he knows that."
It was an answer that stuck in the mind not just because of the mid-2000's Premier League nostalgia (admit it, you didn't think he was going to drop Tugay as the example), but because it neatly surmised why calm and balance is crucial even when the aim of the game is to be attacking and to take chances.
Leadbitter's absence on Saturday actually went some way to prove Johnson's point.
Sunderland lacked composure in possession, constantly giving the ball away under little real pressure from Crewe Alexandra.
In the transition they were too often overwhelmed, the hosts able to counter without any opposition.
On and off the ball, they lacked the control that Johnson demands and that Leadbitter can help bring.
It's why his injury early in the second half poses a problem.
First and foremost, it looks like being a bitter blow for a midfielder who deserved more than anyone the chance to help put an end to Sunderland's long run of losses at Wembley.
Not just for his years of service to the club and his remarkable efforts in the 2018/19 run-in, but also for the way he has managed to reinstall himself in the engine room of the team when few would have predicted it as the first balls of pre-season were kicked.
The exact time frame for Leadbitter’s recovery is not yet known but a period on the sidelines seems inevitable.
Having kick-started his campaign with an outstanding performance in the opening game of the Papa John’s Trophy, his role in the season has been crucial across all competitions and all will hope he gets the opportunity to play in its defining stages.
In the interim, Johnson faces the challenge of getting the balance of his side right.
He will take heart from the thumping 4-1 win over Doncaster Rovers, where Max Power excelled at the base of a midfield three with Josh Scowen and Luke O’Nien providing energy and drive in front of him.
Once his injury crisis in defensive areas eases a little it will no doubt be an option he considers using again, while Johnson has already shown he is willing to gamble by dropping a natural number ten further back.
In the interim, it looks like there will be a big opportunity for Carl Winchester to impress.
Johnson was eager to stress when he brought the former Forest Green captain to the club that he had no doubts both he and Leadbitter could thrive in the same XI.
Winchester’s arrival was nevertheless a recognition that Leadbitter could not be expected to play every game in what is a punishing fixture schedule.
He was recruited because Johnson knew him well from his time at Oldham, but also because the data highlighted his strengths lie in many of the same attributes as Leadbitter has shown over a period of time.
To that end he is the natural replacement for that slightly more withdrawn midfield role, where the emphasis is on keeping Sunderland’s play moving efficiently and helping to protect the defence from the counter-attack.
Winchester’s gametime has been relatively limited so far but there have been flashes of the quality which led Johnson to say he had been playing ‘below his natural level in League One’.
There was an audacious backheel in the build-up to a crucial goal at Ipswich Town, and a Cruyff turn at Burton Albion that should have produced another.
At Crewe Alexandra he was tidy in his play, drawing praise from Johnson in his post-match remarks.
Johnson has Dan Neil, too, who is set to feature for the U23s on Monday as he builds his match fitness.
Both will find themselves with important roles to play in the weeks ahead, as Sunderland look to push for promotion without a player who has beyond doubt proved just how valuable he remains, on the pitch as well as off it.