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
The third baseman was Melvin Kwon
So, in total, the newly improved SimAI Manager did defensive substitutions to put this "best defense" on the field:
Before the update, this would have been the defense the manager put on the field:
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):
Basically replacing the sub-par SS and then shifting the SS to replace the sub-par 3B, rather than replacing the superior defensive 2B.