You are right, I am not a pro sports tog but I am friends with some and follow a few pro togs and I listen to what they say.
besides which i cannot follow your math at all here. lets say there is a particular event to photograph (someone crossing a finishing line. there is a 0.5seocnd window of opportunity, by raw number a 6FPS camera might capture 3 frames and a 4 FPS camera 2 frames, but if the AF system on the 6FPS camera failed then one might have 3 out of focus photos while the 4 FPS camera has 2 perfectly in focus photos. Ever pro sports tog on the planet will prefer 2 perfectly focused photos of a critical event than any number of failed photos. Hence raw FPS is not of critical important, AF performance tracking ability, consistency etc if more important.
there is also the issue of filling the buffer too quickly at high speeds, which is a problem if you machine gun away. Given the same buffer size and a slower shooting rate will cause less problems here, which is one of the main reasons camera have both a continuous High and low speeds because sometimes the low speeds are more useful (although on the pro bodies the buffer is usually sufficient, on some lower end bodies that have high FS the buffer will fill very rapidly).
