I'd rather not have two lefties in a row. Unless you have lefties like Ryan Howard and Chase Utley who don't have as much trouble hitting lefties. If you're learning to hit lefties, they can bring in one lefty to take care of two guys. I'd rather split them up. Eventually they might. Jay is getting better at hitting lefties.
His logic made some sense on the surface, but upon further review Baker's reasoning left many scratching their heads. In the season preceding Baker's quote Jay Bruce actually had better numbers against lefties (.277/.352/.547) than against right-handed pitchers (.283/.353/.476). Ryan Howard (he who doesn't "have as much trouble hitting lefties") posted an OPS of .876 against LHP compared to .899 for Bruce.
Granted, Bruce had struggled mightily against lefties before 2010. Perhaps that season was simply a statistical outlier. Well, it turns out Jay Bruce is actually quite capable of hitting LHP. In fact, the Reds have two of the best lefty-vs-lefty hitters in all of baseball in Joey Votto and Jay Bruce.
Since 2010, only 4 left-handed hitters (including Votto) have hit left-handed pitchers better than Jay Bruce. In addition, Bruce leads all players, regardless of handedness, in home-runs against left-handed pitchers with 42 long balls. Thus, it's safe to say Dusty Baker shouldn't fear the LOOGY.
The reason to move Bruce to 4th in the lineup is more than simply having him hit behind Joey Votto. The real benefit would come from having the Reds four best hitters receiving the most plate appearances. As it is now, one of the Reds worst hitters occupies the 2nd spot in the lineup on a nightly basis. Bruce to cleanup would allow Baker to revert to his original plan with Brandon Phillips hitting second. While not an ideal 2-hitter, BP certainly makes more sense in that spot than Chris Heisey, Zack Cozart or Cesar Izturis. Some might argue that it still makes sense to split-up Votto and Bruce because it allows Brandon Phillips to hit off lefty relievers more often. Ignoring the fact that Bruce has been better against LHP than BP since 2010, Phillips would still see plenty of LHP being sandwiched between Shin-Soo Choo and Votto.
In the end, this simple line-up adjustment would mean more plate appearances for Phillips and Bruce and fewer for the lesser hitters on this team. There's absolutely no reason not to do it.