now imagine i kick you. this is outside you field of vision. now you have to not just focus on my upper body, but also my lower body. that's essentially doubling your field of vision that you need to be aware of.
not only that, but now your stance and cadence is changed. imagine you are an orthodox stance fighter (left foot forward, right foot behind). all your weight is on your lead left leg. if i stand orthodox and use my right leg to go teep your left knee, you might have to switch stances.
tldr;
- your attention is split across more area on your opponents body. makes it easier to get knocked out.
- your fighting stance/cadence/rhythm might be messed up because of annoying teeps