So if you work at doing CrossFit, you're going to get better at...CrossFit. You aren't going to get much stronger at the bench-press; you aren't going to get much faster on the track; you aren't going to deadlift 500 pounds, you're not going to improve your forehand. Sure, if you're so out of shape you can't lift a pencil and you suddenly get a hankering to take up CrossFit, you'll certainly see some changes in performance in many skills. But you could get that effect if you started any kind of fitness program, and these improvements will plateau fairly quickly.
Even though your athletic abilities may very well see some initial improvements on many fronts, CrossFit will never make you a master Olympic lifter, or carve you an astonishingly aesthetic physique, or make you a master sprinter (unless, of course, you have exceptional genetics for any one of those things before you started, at which point--yes--any coach in the world would tell you to jettison all the other irrelevent activities that CrossFit entails and focus on your sport of choice in order to excel further). You simply won't develop exceptional abilities in any athletic endeavor unless you focus specifically on getting better at those things.
Which leads me to my "no progression" complaint. Say you're really into the whole CrossFit thing, and you really want to be able to post some impressive numbers on the site and maybe earn yourself an approving PM from CrossFitChick75. But let's say you're terrible at sprinting. Unless you figure out a way to do some carefully-worked-out sprint progressions in addition to what's posted on the site, you're out of luck, there, Freckles, because sprinting once a week isn't going to make you faster or better or much-of-anything-'er' except exhausteder and frustrateder.
And if you're terrible at, say, deadlifting, you're going to stay terrible at it because before last Saturday, the last time you deadlifted was November 28th, and that was just to test your one-rep max, which I'm here to tell you may be good for the ego but it's not much of a workout. Referring back to the week of workouts, none of the programs listed have been in the rotation for at least a month, and a couple haven't been visited since June, meaning that any specific benefits you got out of the workout a month ago will have evaporated.
So CrossFit isn't the place to turn if you're looking for a systematic way to improve any single aspect of your fitness, be it aerobic conditioning, sports skills, or maximum speed, power, and strength. There are certainly more efficient ways to improve body composition as well.