I think, Mustafiz has lots of potential, but how far he 'll go depends on how much he develops other aspect of his game. Our wickets are a bit scratchy, where the ball grips & his cutters are almost like what Underwood was 40 years back. But, even in IND the wickets are flatter & it 'll not grip that much on grass either, while in AUS/SAF he can't survive with this pace unless he improves his control over swing & seem. AUS wickets are merciless for medium pacers who don't swing it in air - ask Bhuboneshwar, while in UK, unless one seems it of the deck, batsmen 'll play on front foot to cover the swing.
I think, he is 21, around 5'11", still has few more pounds to add. His pace is around 130K, which is good, but need to add another 5-6 KM in average speed to be consistent. But his biggest challenge is the transition between LO to Test. It's quite easy to bowl 4 overs in a T20 or 10 overs in a day & then rest for 2 days. But days 'll come when he 'll be required to bowl 20 overs a day, then open the ball again next morning & in between he 'll have to bowl 4/5 spells in a course of day. With his current physical status, I simply don't see him surviving for a year. At his pace, once batsmen realizes that his shoulders are down, they 'll simply charge down against him.
