I have mixed feelings about defensive shifts, infield and outfield. They're effective when they work, but it's costly if it fails and the batter beats the shift somehow. That has happened to me while playing against the CPU (and I've beaten the extreme left shift as Griffey Jr many times, for example), and I've been a victim of it as well, since I have the defensive shift set to "Auto".
Understanding the mechanics of defensive shifts is not my strong suit. I'm a fan of a team that doesn't shift a whole lot (lifelong Tigers fan here), so I'm not sure what to think about shifts.
So what are your preferences on using (or not using) defensive shifts?