His findings were, by most measures, alarming: pulse rates that, at times, spiked to four times their ordinary level; blood pressures that soared to dangerous levels. The doctor who carried out the experiment, Dorian Dugmore, was in no doubt as to the warning contained within his findings. Every week, he said, “these guys are putting their hearts on the line.”

It is hardly a surprise, then, that there are physical consequences to that strain. Some resist for a little longer than others. José Mourinho arrived in English soccer with a head of raven-black hair; it was a few years before it turned salt-and-pepper. Jürgen Klopp’s beard is flecked with gray these days, too, four years after he joined Liverpool. The color, by contrast, seemed to drain from Ole Gunnar Solskjaer within months of taking over at Manchester United.

For now, though, Frank Lampard seems almost immune. He is seven months into his career as a Premier League manager, and he has spent most of it smiling. The long hours might have added a little to the shadows under his eyes, but his mood is unfailingly cheery. He skips up the stairs onto his dais at news conferences. He has a disarming knack of chuckling and charming at even the most challenging, impertinent questions, a well-worn recipe of wry grin, one-liner, and then, “No, but seriously.”

Chelsea’s Antonio Rudiger celebrates scoring their first goal with teammates.(Reuters/John Sibley)

For a man who spent much of his career learning at the knee of Mourinho, Lampard’s style is unexpectedly chipper. He is not, unlike his mentor — and, indeed, like essentially all of his peers in the Premier League these days — much of a brooder and a bristler.

In his first few months, it was easy to explain why. Lampard, uniquely in this phase of Chelsea’s history, appeared to be under no immediate pressure whatsoever. The club accepted, it seemed, that he would have to learn on the job to some extent: his only previous managerial experience, after all, had been a season with Derby County in the championship.

The club was operating under a FIFA-imposed transfer embargo; it had lost its lone superstar, Eden Hazard, to Real Madrid; it was determined to promote some of the brightest talents from its youth program — the best in England for almost a decade — now that its hand had been forced. It knew there would be bumps in the road: that opening day defeat to Manchester United; the early troubles in winning games at home.

Youth has always bought managers time. Fans are, broadly, willing to suffer a little — and only a little — today if they feel that the promise of tomorrow is genuine. For once, and in a complete volte-face from its usual modus operandi under Roman Abramovich, Chelsea seemed to agree. This would, the line came again and again, be a transitional year. Not quite a freebie, but not far off, either.

On the face of it, the gamble has worked. Chelsea sits fourth in the Premier League, possessed of a comfortable cushion over the gaggle of teams — Manchester United, Tottenham, Wolves and Sheffield United — in pursuit.

A 2-2 tie with Leicester City on Saturday meant the gap to third place remained at eight points, most likely too much to be overhauled, but no matter: a return to the Champions League would represent a more than acceptable start for Lampard. His squad already has reached the last 16 of this year’s competition, another box ticked. Getting past Bayern Munich later this month would, if anything, be exceeding expectations.

His young players, too, are flourishing. Tammy Abraham, for so long the avatar of all that was wrong with Chelsea’s approach to youth, has scored 15 goals in his long-awaited first season as the club’s first-choice striker. Midfielder Mason Mount and winger Callum Hudson-Odoi have played their way into contention for England’s national team. Reece James has adapted so well to the Premier League that he is currently forcing Cesar Azpilicueta, the club captain, to play out of position.

That is how it seems. It is not, necessarily, how it is. Lampard was pleased Saturday with what he described as a “fair” point against Leicester — a team, after all, one place higher in the league — but it meant that Chelsea has now won only four of its last 13 Premier League games. That it remains secure in fourth place is not, increasingly, through its own merit, but through the failings of Manchester United and Tottenham, in particular.

He remains adored by Chelsea’s fans, of course — they sang his name here, lovingly, as he trotted over to thank them for their support, his fist clenched in appreciation — but that early-season aura of happy-go-lucky insouciance is starting, for the first time, to dissipate.