That's exactly what the rule is for. Defenders pursuing the runner need to keep focused on the runner. Blockers know that so they take advantage and blow them up. When blocking outside the focus of the defender it takes very little contact to take them out of the play. This is exactly the kind of block this new rule was designed to eliminate. In this case you could also make a case for unnecessary roughness regardless of blindsided because he's not going to make a play as the runner is in or about to score so there is no reason to even block him.
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