TBH, their success ratio may only better as they are essentially the only ones that do it.
This is a list of the players 18 or under on Test debut over the last 20 years.
One pattern is clear and that is the vast majority of young debutants are from the subcontinent. Also, that for supposedly super talented players that demand to be selected so early they are not particularly successful.
Apart from a couple of names, the majority are ordinary cricketers. In fact NZ may have the best record in converting young debuts to decent cricketers compared to anyone else on the list.
Apart from occasional 'once in a generation' players, selecting young teens is usually the preserve of the desperate.
Code:
Player Age Team Opposition Ground Match Date Scorecard
Tamim Iqbal 18y 290d Bangladesh v New Zealand Dunedin 4-Jan-08 Test # 1859
Mushfiqur Rahim 16y 267d Bangladesh v England Lord's 26-May-05 Test # 1751
Shahadat Hossain18y 292d Bangladesh v England Lord's 6-May-05 Test # 1751
Nazmul Hossain 17y 73d Bangladesh v India Chittagong (MAA)17-Dec-04 Test # 1727
Aftab Ahmed 18y 351d Bangladesh v New Zealand Chittagong (MAA)26-Oct-04 Test # 1717
Nafees Iqbal 18y 354d Bangladesh v New Zealand Dhaka 19-Oct-04 Test # 1715
Enamul Haque 16y 320d Bangladesh v England Dhaka 21-Oct-03 Test # 1665
Anwar Hossain 18y 363d Bangladesh v West Indies Dhaka 8-Dec-02 Test # 1630
Alok Kapali 18y 208d Bangladesh v Sri Lanka Colombo (SSC) 28-Jul-02 Test # 1611
Tushar Imran 18y 220d Bangladesh v Sri Lanka Colombo (SSC) 28-Jul-02 Test # 1611
Talha Jubair 16y 223d Bangladesh v Sri Lanka Colombo (PSS) 21-Jul-02 Test # 1609
Mashrafe Mortaza18y 34d Bangladesh v Zimbabwe Dhaka 8-Nov-01 Test # 1566
Mohammad Ashraful17y 61d Bangladesh v Sri Lanka Colombo (SSC) 6-Sep-01 Test # 1561
Mohammad Sharif 15y 128d Bangladesh v Zimbabwe Bulawayo 19-Apr-01 Test # 1543
Ranjan Das 18y 119d Bangladesh v India Dhaka 10-Nov-00 Test # 1512
I Sharma 18y 265d India v Bangladesh Dhaka (SBNS) 25-May-07 Test # 1833
Piyush Chawla 17y 75d India v England Mohali 9-Mar-06 Test # 1788
PA Patel 17y 152d India v England Nottingham 8-Aug-02 Test # 1612
Harbhajan Singh 17y 265d India v Australia Bangalore 25-Mar-98 Test # 1413
SR Tendulkar 16y 205d India v Pakistan Karachi 15-Nov-89 Test # 1127
DL Vettori 18y 10d New Zealand v England Wellington 6-Feb-97 Test # 1354
Yasir Ali 17y 323d Pakistan v Bangladesh Multan 3-Sep-03 Test # 1658
Salman Butt 18y 331d Pakistan v Bangladesh Multan 3-Sep-03 Test # 1658
Imran Farhat 18y 292d Pakistan v New Zealand Auckland 8-Mar-01 Test # 1533
Qaiser Abbas 18y 192d Pakistan v England Lahore 15-Nov-00 Test # 1513
Irfan Fazil 18y 131d Pakistan v Sri Lanka Karachi 12-Mar-00 Test # 1489
Imran Nazir 17y 78d Pakistan v Sri Lanka Lahore 4-Mar-99 Test # 1447
Shahid Afridi 18y 235d Pakistan v Australia Karachi 22-Oct-98 Test # 1427
Fazl-e-Akbar 17y 129d Pakistan v South Africa Durban 26-Feb-98 Test # 1403
Hasan Raza 14y 227d Pakistan v Zimbabwe Faisalabad 24-Oct-96 Test # 1337
Shahid Nazir 18y 318d Pakistan v Zimbabwe Sheikhupura 17-Oct-96 Test # 1336
Shadab Kabir 18y 256d Pakistan v England Lord's 25-Jul-96 Test # 1330
Saleem Elahi 18y 353d Pakistan v Australia Brisbane 9-Nov-95 Test # 1311
Saqlain Mushtaq 18y 253d Pakistan v Sri Lanka Peshawar 8-Sep-95 Test # 1304
Ata-ur-Rehman 17y 68d Pakistan v England Birmingham 4-Jun-92 Test # 1189
Zahid Fazal 17y 5d Pakistan v West Indies Karachi 15-Nov-90 Test # 1154
Aaqib Javed 16y 189d Pakistan v New Zealand Wellington 10-Feb-89 Test # 1115
PR Adams 18y 340d South Africa v England Port Elizabeth 26-Dec-95 Test # 1320
CM Bandara 18y 147d Sri Lanka v New Zealand Colombo (RPS) 27-May-98 Test # 1415
DNT Zoysa 18y 298d Sri Lanka v New Zealand Dunedin 7-Mar-97 Test # 1358
JE Taylor 18y 363d West Indies v Sri Lanka Gros Islet 20-Jun-03 Test # 1648
AG Cremer 18y 109d Zimbabwe v Bangladesh Chittagong (MAA)6-Jan-05 Test # 1733
E Chigumbura 18y 53d Zimbabwe v Sri Lanka Harare 6-May-04 Test # 1698
BRM Taylor 18y 90d Zimbabwe v Sri Lanka Harare 6-May-04 Test # 1698
T Panyangara 18y 198d Zimbabwe v Sri Lanka Harare 6-May-04 Test # 1698
H Masakadza 17y 352d Zimbabwe v West Indies Harare 27-Jul-01 Test # 1553
T Taibu 18y 66d Zimbabwe v West Indies Bulawayo 19-Jul-01 Test # 1551
HK Olonga 18y 212d Zimbabwe v Pakistan Harare 31-Jan-95 Test # 1285