Charrington admits that back-to-back 17th-place finishes represent a failure the board will not attempt to minimise.
Spurs survived relegation on the final day of the Premier League season, with Roberto De Zerbi's side beating Everton 1-0 at home while West Ham United lost the battle at the other end of the table. The margin was two points.
The closeness of the escape did not soften the tone of Charrington's message.
"Two 17th-place finishes in a row is not acceptable, and we will not dress it up as anything other than falling well short of what this club expects," he wrote.
Charrington acknowledged that the club's problems ran deeper than results alone. Football decisions had been driven by the wrong priorities, the right expertise had not been placed in key roles, and squad-building had repeatedly fallen short of what the Premier League demands. The Lewis family, majority owners of the club through ENIC, had authorised a reset last September following the departure of long-serving chairman Daniel Levy.
"Football success had not been driving our decisions," Charrington admitted.
The chairman confirmed that a restructured leadership team is now in place, with further appointments due in the coming weeks. De Zerbi has signed a five-year contract as manager — a length of deal the letter described as a direct expression of the board's commitment to a sustained rebuild rather than another short-term fix.
De Zerbi took charge in March as the club's third manager of a turbulent season, succeeding Thomas Frank and interim boss Igor Tudor. The Italian had previously managed Brighton & Hove Albion and Marseille before becoming available following a mutual parting from the French club in February.
Midfielder James Maddison acknowledged the significance of De Zerbi's impact on the dressing room.
"I am really happy for the manager who came in and steered the ship clear," Maddison said. "Because I think without him, it could have been doom and gloom, if I am honest."
Charrington also moved to end speculation over the club's future ownership, stating that Tottenham Hotspur is not for sale and that the Lewis family regard their involvement as a long-term responsibility.
Planned investment will cover multiple transfer windows, with this summer described as a first step. The academy pathway, the women's team and the medical and performance departments were all identified as areas earmarked for improvement.
The letter closed with a personal acknowledgment of what Charrington described as the distinctive loyalty of the club's supporters.
"I have seen it over and over again in the last nine months, across every generation, in every conversation," he wrote. "Even in the darkest of seasons, you showed up and carried this team."
Spurs will now plan for a 2026-27 season with Champions League football a target — an ambition the club has not yet come close to matching on the pitch.