blindside

The Japan Times Dec. 12の記事から引用します。

Investors rush to update yen playbook after Bank of Japan’s surprise shift
The yen surged 4.8% on Tuesday after the BOJ blindsided the market by raising its cap on 10-year bond yields to 0.5% from 0.25%.

ラグビーでスクラムを組む際、スクラムの位置が中心近くではなく左右のいずれかのサイドに片寄っている場合に敵も味方もバックスが少ない側をブラインドサイドと呼んでいますが、上の記事の "blindsided" は何でしょうか？

・Collins Dictionary: If you say that you were blindsided by something, you mean that it surprised you in a negative way.: He complained about being blindsided by the decision.
・Cambridge English Dictionary: to surprise someone, usually with harmful results: The recession blindsided a lot of lawyers who had previously taken for granted their comfortable income.

ラグビーでもブラインドサイドを攻めるのは意表をつく意図がありますね。