As someone mentioned earlier its not that they, save for Jones, cannot hit LHP's, its their aggression that's getting them out. Duke and Capuano have pretty good stuff, I wouldn't call them soft-tossing junkballers, Mulder and Davis are soft tossing junkballers, all of these LHP's take the same approach. Live on the outer third of the plate, counting on the agressive hitter trying crush and pull everything thereby generating GB's to 2b, SS, and 3b. Its the hitters who exercise some patience and look to take the pitch the other way that smoke these guys, you'd think after seeing the same thing over and over again the Cub hitters would figure it out.