He broke UZR because of his shifting. IIRC they ended up taking out plays that are fielded more than a certain distance away from the usual starting position for a given fielder so Zobrist and a few others wouldn’t get OOZ credit for balls hit in the RF gap as a 3B.
This is from Brandon Bailey's blog. https://brandonbailey1994.com/2019/03/19/how-do-i-top-that/
It mirrors some of the things player development was doing with pitchers in the Orioles system in 2019.
"What I didn’t understand was that the Astros player development staff was purposely challenging me to get out of my comfort zone, propelling me to throw more curveballs and sliders rather than my bread & butter fastball-changeup combo. This new challenge forced me to deal with some failure and adversity; and while no player ever wants to be told that they have blaring weaknesses in their game, sometimes it’s the brutally honest conversations that lead to the biggest improvements.
“We’re not preparing you to have success in the Carolina League,” my High-A pitching coach Drew French explained to me one day after a tough outing, “We are preparing you to have success in the big leagues.”"
I have not studied this topic, so I cannot get specific. However, after having watched MLB operate for many years, it just might be a perceived short term solution to a perceived problem, but I would bet that in the long run it will not help the players. Sure some players salaries MIGHT rise slightly, but there will be fewer players, fewer teams, and less help to local economies as the result of this proposal. Remember. minor leagues are the life blood of MLB.