"Scallopping" such as that is normal, front and rear. I've had many tires do it.
Dave Moss, a suspension guru, attributes it to less than optimum damping. At the track, for a fee, he "reads" tires and in my experience his re-setting of a bike's suspension and tire pressures can improve tire longevity. Too much or too little damping on either side - rebound or compression - causes wear just before or just after the tread sipes. That's what your pics show. On a track tire, you'll see balled up rubber deposited in the wake of the sipes. It has to do with the tearing distortion torque applied at the rubber/road junction by acceleration on the rear or the decceleration on the front. I've seen the rate of wear change from session to session after he looks at tires, and when he re-sets air pressures and tweaks the pre-load or damping of the suspension units. I've seen those balls of torn/melted rubber go away and be replaced by a pattern of smooth ripples - that's what he's looking for. You can't replicate it on the street, the tires just don't get hot enough.
