'Fraid I'm going to have to disagree with that. While it is true that relatively recent evidence has implicated Broca's area in the comprehension of syntactical relationships, it is also certainly involved in the motor output of speech. My take is that Broca's area probably encompasses multiple "areas" which are architecturally indistinguishable (the traditional way of delineating areas of the brain) but functionally distinct. The lack of fluency in Broca's patients cannot be explained by grammar problems, but demonstrates an inability of the brain to generate and carry out the complex stereotyped motor programs necessary to produce speech.
The primary motor strip is far from the only structure in the nervous system involved in motor output. There is remarkable complex interaction between the (I'm probably forgetting some) cerebellum (coordination feedback to make sure the body is actually performing the action it wanted to), basal ganglia (initiation of movement, among other roles), primary, supplementary, and premotor areas, the visual system including primary and secondary visual areas of cortex (visually guided actions, mapping of environment) as well as subcortical tectum (important for orienting reflex actions) and even the spinal cord which stores many complex motor patterns on its own in spinal pattern generators (the way this was demonstrated is pretty neat: cats with transected spinal cords, when supported above a treadmill, walk with their hind legs).
While the primary motor cortex is responsible for the direct output to the motor neurons (or spinal central pattern generators), Broca's area is required in order for the pattern of complex and coordinated oropharyngeal movements required to speak to be produced (it's like the programmer...the motor strip follows the program written by broca's area). Similar to how the supplementary motor area coordinates complex and bilateral hand movements and sends the output to the primary motor strip to be executed.
It's interesting that Broca's area also seems to have mirror neurons in it...just as the supplementary motor area does. Mirror neurons are neurons which fire as if they are coordinating a specific action when that action is seen. E.G. I see you raise your hand, the mirror neurons in my supp. motor. area will fire in the exact same way they would if I were to acutally raise my hand in imitation. It's a sort of practice execution of the program, without acutally telling the motor strip to "GO." Broca's does the same thing (which I think is also used as evidence that it is involved in speech comprehension).
Overall the research here is pretty complex, and a lot of it has been focusing on parceling out parts of the brain into smaller and smaller "subareas" each responsible for a different function (thank you occasionally mediocre fMRI studies for that), but as long as we talk about Broca's area as the area laid out by Broca (or Broadmanns 44 and 45), it will encompass an area of cortex which is important for motor output. It's called non-fluent or expressive aphasia for a reason...while there is now appreciated to be a receptive aspect to the language dysfunction, the classical idea of Broca's as a motor problem is still valid, based on any evidence I've ever seen.
Fun discussion. Like you said...largely irrelivent to the practice of EMS, but super interesting nonetheless.
