Don't be so gullible.
Wisconsin is indeed ranked #2 by SAT scores, but the rankings for the low scores are inaccurate.
Here are the actual scores and the actual ranking at the "low end" of the scale up as far as Virginia (which actually ranks above unionized blue state California, New Jersey, Maryland, Rhode Island, Delaware, Pennsylvania, New York, Hawaii, Maine and the District of Columbia):
33 Virginia 68% 511 512 498 1522
34 California 49% 500 513 498 1511
35 West Virginia 18% 511 501 499 1511
36 New Jersey 76% 496 513 496 1506
37 Maryland 69% 500 502 495 1498
38 Rhode Island 66% 498 496 494 1489
39 North Carolina 63% 495 511 480 1487
40 Nevada 42% 501 505 479 1485
41 Indiana 63% 496 507 480 1484
42 Delaware 71% 495 498 484 1478
43 Pennsylvania 71% 493 501 483 1478
44 Florida 59% 497 498 480 1476
45 Texas 51% 486 506 475 1468
46 New York 85% 485 502 478 1466
47 Georgia 71% 490 491 479 1461
48 South Carolina 67% 486 496 470 1453
49 Hawaii 58% 479 502 469 1451
50 Maine 90% 468 467 455 1391
51 DC 79% 466 451 461 1379
All Students 46% 501 515 493 1509
When you look at the actual data, most of the worst school districts actually are unionized with the very worst---DC, Maine, and Hawaii---being unionized.
states with the very worst SAT scores have unionized teachers