Probably that.
If you're faster, you dig in first, evade the attack. Then 2nd turn you dig out first, and get hit by the attack.
If you're slower, you get hit by the attack, then you dig in. And in the 2nd turn, you'll evade the attack, and dig out to hit.
In my scenario, I'm always the faster party, so this might be a wrong guess. (this can be testfied by my first move with other skills)