Tang is using a book. I don't know which one.
Here is the analysis of every number which ever fell in the 14 draws (one week) after 921 straight in Virginia.
Numbers Which Fell within 14 Draws of 921 in Virgnia
Tier 5
134(134,143,314,341)
Tier 4
518(581,581,815) 587(758,758,785)
Tier 3
067(670,706) 068(086,680) 099(099,909) 208(208,802) 296(629,962) 362(623,632) 406(406,460) 570(570,750) 688(688,886) 889(889,988)
Tier 2
006(600) 016(160) 021(210) 025(250) 043(430) 044(044) 074(470) 077(707) 084(408) 093(309) 104(410) 114(141) 137(371) 183(813) 192(921) 223(232) 255(255) 274(742) 276(726) 279(297) 349(493) 368(638) 375(375) 384(438) 437(473) 471(471) 492(924) 516(651) 605(650) 606(660) 654(654) 679(796) 727(772) 746(764) 763(763) 784(847) 957(975)
Tier 1
000 035 050 063 073 079 108 109 131 133 136 154 166 189 220 224 246 261 270 284 290 298 300 312 334 345 353 378 379 380 393 452 484 515 532 536 545 553 559 583 649 652 655 663 669 699 711 722 766 773 794 800 817 839 855 864 869 885 887 890 895 917 925 994 999
Most-drawn straights:
471 appeared 2 times in the list
375 appeared 2 times in the list
406 appeared 2 times in the list
044 appeared 2 times in the list
570 appeared 2 times in the list
134 appeared 2 times in the list
581 appeared 2 times in the list
255 appeared 2 times in the list
654 appeared 2 times in the list
099 appeared 2 times in the list
688 appeared 2 times in the list
889 appeared 2 times in the list
758 appeared 2 times in the list
208 appeared 2 times in the list
763 appeared 2 times in the list