formerflanker
Ken Catchpole (46)
The leading teams in professional contact sports use a comprehensive mix of quantitative and qualitative stats.
The accuracy comes because they are captured from detailed video analysis.
Each of the sports tracks very specific actions related to that player's position and the team's performance.
The best of the best teams use this performance criteria and stats analysis in decision making for team selection, recruitment and retention.
The players know what's important, know they're going to be measured performing these actions, and accountability results.
Exceptionally good or poor examples are shared with individual players via edited video footage online so they can review them from wherever.
Accurate and relevant stats are invaluable.
The beauty of the rigour you mention is that players and coaches can differentiate between specific on-field actions. For example, a lock who makes two line breaks may be rated below a no8 who took the ball into contact five times, attracting 3 defenders each time, but doesn't break the line at all.
The qualitative aspect must be considered too - Hooper's kick-off chase and tackle v France was an energising action for the whole team and supporters.
Thanks for your explanation IIWIS.