Pilot road 4 m821

Little feedback..... the pilot road 4s I had fitted the rear has squared off to an unpleasant level after 3000 miles with a very defined edge. Sure the 1000 miles of motorway riding last week wouldn't have helped but my question is this.... WTF am I doing wrong to get such poor life out of the rear tyre?! Front has worn well this time and has plenty of life left but I'm going through rears like you wouldn't believe!

I got 6300 out of a rear from Metzeler on a 675r (tuned) and ridden in largely straight lines and it was still like new in terms of shape... I don't accelerate hard instead I carry my speed usually 50-70mph on my commute.... so I don't know what I'm doing to kill the rear tyre at 3000 miles on the Ducati.