An aggressive swing is not a good swing.
A balanced swing that's quick through the zone is a good swing.
Being aggressive as a hitter doesn't mean chasing bad pitches, it means attacking pitches in your hit zone.
There are very few low BB/High K successful hitters, there are more low BB/low K hitters, because they're good at making contact so they never get to ball 4.
PItchers don't want to throw anything in Franco's sweet spot, as long as he chases bad pitches they don't have to - batters don't draw walks because pitchers are trying to "avoid" them, they draw walks because they don't swing at bad pitches, get ahead in the count and pitchers don't want to groove fastballs. Fall behind in the count, and a pitcher will try to get you to chase a low breaking ball or high fast ball.
As I pointed out, Joseph and Rupp also have to become more disciplined, but they're more willing to hit the ball the other way.
At this point of the season I don't care about BA or OPS, I'm looking at form, when Franco grounds an outside pitch through the SS/3B hole, that's bad, when he lines out to RF on an outside pitch, that's good. When Franco swings at a breaking ball in the dirt or a high FB, that's bad, when he smokes an inside breaking ball to the LF like last night, that's good.
Very few hitters can hit perfect pitches, very few pitchers can throw 3-4 perfect pitches to each hitter they face.
So it comes down to hitters patiently waiting/forcing a mistake, and the pitcher eventually making one.
Good hitters mash those mistakes, bad hitters foul them off.