The biggest cause for this question is not correctly understanding the SCARS Offensive Mindset®. The SCARS Offensive Mindset requires you to make both Mental and Physical changes to your action. A strike isn't just a block called a strike, that's a lie. Furthermore, the particular movement in question is only one of many ways we deal with punches and other attacks.
If you're mentally thinking defensively, your physicality (including your vision) will force your body to move defensively, which is slower and forces you to exert about 35% less power than you would if you were functioning in an offensive state of mind (and that's just the tip of the iceberg).
Worst thing you can do is utilize your focus vision by staring at the attacker's fists in a defense posture and try to time a "circular strike". This is not what we train you to do. Doing that applies none of the SCARS principles.
Also, you should never standout with your "hands up" waiting for a person to strike you. Even if you are a professional and must wait for an assailant to move first. Doing so creates distance and allows the attacker to see everything you are about to try and do.
Understand, SCARS is not a sport system, like it or lump it, if you are utilizing defensive posture and terminology you are training for sport and are not at all offensive. No matter how aggressive you are, even if you aren't fearing one bit, you are still one move behind someone who is completely 100% offensive.
It is also a misnomer that if you are 100% offensive you are utilizing aggression. Again someone who thinks that is going back to sport application of Offense and Defense in a game.
Once you understand how to strike a punch it becomes a mute subject, and is one of the least of the real threats a professional killer will attempt to harm you with.
Understand SCARS was developed within the Special Forces community, it was designed to utterly destroy the human body by systematically breaking down an attacker's ability to think and function.
If you watch a SCARS lesson, we break it down step by step, we stand still and strike because we want you to see all aspects of the lesson. So, when one goes to practice one may forget the "Full Speed" version where we don't stand "out" or "still". Our goal in our lessons is to make you make those movements so powerful and hit the attacker with your body so hard they temporarily hesitate while you keep hitting (or whatever the movement is we show) so that there is absolutely NO opportunity for the attacker to get a chance to move again.
If you haven't been taught by us on how to do this then it will not make any sense.
We have a whole system of training just on this topic that lays out how to make this happen in its entirety.
You can find this information below in one of three places.