Wide baffle speakers are better than narrow

And it would be more correct to specify baffle dimensions relative to wavelength, not some arbitrary number....

But the physics of a large baffle are pretty clear:

constructive and destructive interference average out peaks and dips in frequency response

they are louder aka more efficient, stick em in a corner for MAX effect....

they destroy time and phase information and are therefore lossy

all else being equal the more narrow the front baffle (and the shorter for that matter) the better the speaker will image, have less cabinet resonance, less diffraction and phase issues, better dispersion and be less demanding to position.  
the goal is to minimize the surface area of the front baffle and by doing so minimize the amount of frequencies that is reflected back to the listener.  mixing direct and reflected sound causes phase distortion, frequency imbalances and requires more complicated crossovers to manage.  

...yeah, I used to headhunt @ headshops, in those heady daze..at the head of the list wuz Hedley's, a place to hang one's head and head out back, where the head honcho, Edmond Heddmen used to ....

...and I'm still baffled by the basics of baffles....wide bafs, narrow bafs, bafs on my belfry, bafs 'bout the back barn backyard...