Piastri carved time out of Leclerc through the tightest part of the circuit — Turns 10 through 14, the sequence that decides who has the mechanical grip to rotate the car without scrubbing speed. He was three and a half tenths faster there. That is not a small margin. That is the difference between a good lap and pole position.
Leclerc gave it all back in the middle sector. He was 0.079s faster through Turns 5 to 9, the section with two track limits deletions during the session and nowhere to hide if the car won't turn. He also took 0.014s in Sector 1. Those margins sound modest. They added up to pole.