The defensive AI often does not really sparkle with genius. In my league, there's a player with blue or green ratings at all outfield positions that several AI teams have insisted on playing at third base - for years! He is *terrible* at third base. He spent two seasons with my Raccoons, where I used him as an outfielder - fine defense, something everybody can enjoy. Once he left for elsewhere, he was deployed at third base again.
I also see so many shortstops with orange ratings for that position that make 20+ errors a season. You can't have everything, but middle infield should be the area where you want as much defense as possible.