On matchday 12 of the 24/25 season Tottenham beat Man City 1-4 to move to 6th on the table. 4 points off 2nd place with a G/D of +14 (for comparison City in 2nd position had a G/D of +5).
Half an hour after the end of that game it was revealed that Vicario had a broken foot. With Romero and VDV already out with injury and Udogie subbed off in that game for an injury - the first choice Back 5 would not play together in the league again.
They would only play together in the Europa League from late March onward. When they did play together Tottenham didn't lose a game and went on to win the Trophy.
I think it's fair to say Postecoglou was certainly doing well enough at that time and that injury and lack of depth in the squad was the reason for the collapse in the league that would follow.