He had starting SS (!)
Kevin Itou (68-72-88-77) slide over to replace
Eddie Gumbert (79-71-81-82) at 2B.
The player that came in to replace Itou at SS was
Cesar Borbon (76-71-81-82).
The third baseman was
Melvin Kwon (66-60-63-57).
So, in total, the newly improved SimAI Manager did defensive substitutions to put this "best defense" on the field:
SS: 76-71-81-82
2B: 68-72-88-77
3B: 66-60-63-57
Before the update, this would have been the defense the manager put on the field:
SS: 76-71-81-82
2B: 79-71-81-82
3B: 66-60-63-57
If the update was working as intended, I would have hoped that the manager would have put this defense on the field (assuming the owner allowed for all defensive replacements):
SS: 76-71-81-82
2B: 79-71-81-82
3B: 68-72-88-77
Basically replacing the sub-par SS and then shifting the SS to replace the sub-par 3B, rather than replacing the superior defensive 2B.