My two cents on Hasnain:
First of all, I am a huge proponent of throwing them in while they're young and raw! That has what made Pakistan cricket - well . . Pakistan cricket! We are known for it . . and we have produced gems like that!
Now coming to Hasnain . .
I don't have the statistics, so if anyone does, that would be great . .
I have watched 3 of his spells . . and it seems the 151 was an aberration . . Most of his balls are in the 140 to 144 region . . which to me, is hardly anything to rave about unless you've got skills to go along with it . . either swing . . or bounce (like Shaheen) . .
All of Hasan, Wahab and Shaheen are also bowling quite a few deliveries in that range . .
Can Hasnain get quicker? Absolutely! But it seems either he isn't there yet or he only pushes himself on a few deliveries . .
But my analysis is:
1. His run up seems a bit off . . his steps are too long which restricts him from gathering pace to the wicket . . If he can get a smoother run up, perhaps his average speed will be consistently higher
2. His release doesn't aid any swing at this point . . he has a sling which could be helpful in his effectiveness in reverse swing given the right conditions
3. At an average speed of 142 kph with his current skills, he won't have a good time of it at the international level where the batsman are not going after him like T20. .
All in all, he has the talent . . I am all for his inclusion . . but he needs to pick up those skills, get his average speed higher and I have no doubt he will given he is only 18!
Good luck to him! I hope he succeeds and has a long career for Pakistan!