The other night I was training with my coach and was made to do several rounds of boxing sparring with him. Going into the ring, one of the other coaches told me to keep my hands up and against my head at all times in what we call in my style a "turtle block." Not knowing what was coming my way, I didn't feel the need to use the turtle block as my guard against Mark. I was soon disabused of any such notion.
My coach is a former pro-boxer, as some of you already know. And he decided that night it was time to put more pressure on me. Without hitting me hard enough to cause injury (though hard enough to cause real discomfort), he proceeded to lay the beats on me for three rounds.
At first, when I stayed in a more traditional, more open guard, Mark just punched right through my guard, landing blows to my head with his own fists or simply by punching MY fists into my own face. After a minute of this, I buckled down and put my hands up into my turtle block position so I could absorb all his blows and throw a few of my own punches when the opportunity presented itself.
In this kind of boxing, there is really no blocking at all. It's pretty much just either absorbing the blows with a solid guard or damage control (i.e. keeping the chin low and actively taking the blows on the forehead where the head is strongest). All the more reason to train yourself to fight the flinch.
I was later told though that I can keep my lead arm out a bit more so that I can snap out my jab more easily as long as I keep the arm quite firm so that my opponent's blows to punch through my guard or cause me to hit myself in the face. I practiced this a bit later on and found it an effective alternative to simply maintaining the turtled position. And as far as MMA goes, I found that this firm guard allows me to absorb blows more effectively when entering an opponent's space for throws and takedowns.