He has a sr of 80 in first class cricket and no matter how good you are you cant score that quickly in test cricket.
Virender Sehwag
Mat Inns NO Runs HS Ave BF SR 100 50 4s 6s Ct St
Tests 104 180 6 8586 319 49.34 10441
82.23 23 32 1233 91 91 0
despite poor form in the last year and half
Then there is Kapil dev and Gilchrist with 80 SR with 5000+ runs
So if QDK can make it at INTL level with the same methods it means you would have a match turner someone who can take the game away in a couple of session, sure he wont come good always but when he does he would make it count!
You wouldnt know until you try, i mean QDK is young throw him in for a series or two see if he can adapt if not let him go work on it in FC! Its a win win for SA either way !