I think you may have misunderstood the article.

There were two tests, one to distinguish strad from modern, one to score which instrument musicians liked best. In the first, they didn't get 31 of 33 wrong, they got 33 wrong and 31 right, virtually a 50/50 split. In the preference test, modern violins placed first and second, with the top place substantially above the others, though the article doesn't give the full score breakdown.