Manual timing is the default mechanic
The official report describes all dunk attempts as manually timed. A developer answer archived by NBA2KLab says offline play can disable dunk timing, so mode and settings still matter.
Defender position stays live
The logic-driven meter continually reevaluates defender positioning after takeoff instead of freezing the target at the start.
Timing is only one input
The official mechanic directly confirms positioning, defender and timing relationships. Exact attribute and animation thresholds remain an eligibility check, not a number guessed here.