I'm sure it's defense-related. We all know Jake is a pretty terrible outfielder, and Lou likes to go with defense at times. Not that UZR is everything, and the sample sizes are small, but Fox has a -27 UZR in left field. Even still, the Cubs should be playing him every day at this point so they can audition his bat for a trade to an AL team. There's no reason for him to ride the bench.