Thank you for your implicit admission you don't know how advanced baseball metrics are measured. It's not subjective, each batted ball is measured and compared to batted balls from the past.Al Bundy;1743653 wrote:It just depends whether you want objective or subjective stats. "How tough a play is to make" is a subjective stat.
This is just an explanation of outfield stats, but maybe it will enlighten you that it's not a bunch of people sitting in a room deciding "what's tough", it's a statistical based model based on the actual output of what happened on the field.
http://grantland.com/the-triangle/2015-mlb-kansas-city-royals-san-diego-padres-outfield-defense-lessons/
Scroll down here for a breakdown of Machado v Arenado when it comes to defensive plays. Consider this a primer on infield stats
http://grantland.com/the-triangle/2015-mlb-who-ya-got-manny-machado-nolan-arenado-third-base-young-star-edition/