Defender's excel at shrugging off one bad roll. They usually cant do it multiple times. Just like how you deal with aces you need multiple attacks, one or two to burn the tokens then another to actually hit them. Any ship with a focus or evade and 3+ agi is hard to hit as it is let alone if they have both. However 3 agi on its own isnt that dependable.
My defenders never die in a single round even if i roll badly because of those tokens vs how many targets im dealing with. But ive lost them or had them at 1hp by the 2nd round many times. Focus fire, if you cant hit them with more than 1 ship then dont even try unless you dont have another shot. Better range2 or even 3 with no tokens than range1 with both tokens (defender's side)