Asif is a genius - some of his movements actually defies the laws of physics.  I think, he is born with some abnormalities in his wrist, otherwise his away cutters (ball that drifts away from right-handers & cut back sharply off the seam) are impossible to master.  I have seen PAK bowlers doing fancy things with old ball, like Imran could swing inwards & then swing away after pitching (right-handers) or Wasim & Waquar could reverse it both ways in air, but a mixture of swing & cut is unique.  I have seen the ball of VVS & Ponting (?) at Cape Town (?) several times in slow mo, but no clues yet.  I think, Asif is one of those bowlers who could be lethal even at 35 & at 125km speed, particularly in England.  At his prime, for few series he was more skillful than Jimmy & more accurate than Styen.  In 2010, in 12 Tests in NZ, AUS & ENG, I think he took ~60 wickets, against top 3 of 4 sides in World at their home, and PAK fielders dropped another 20 sitters..... 
If AA pair can reach to their level of 2010, backed by Wahab, Yasir, Rahat; PAK 'll be a formidable Test side in UK & down under, as long as the catches are taken.  That'll easily be the best Test attack in contemporary world, by some distance.