varsity level in high school and am a big fan of both, and have watched both extensively my entire life, so I'm not biased in either direction.

But I will say that the single most important factor in getting to the NBA is height -- if you are anywhere near average height, or below, your odds of making the NBA are extremely low, regardless of your athleticism or shooting ability. To get to the top soccer clubs in the world, OTOH, athleticism is the #1 consideration, along with actual soccer skills (well, maybe not so much in England or Germany ). Since height is almost irrelevant in soccer, they are drawing from a much larger pool of elite athletes than does the NBA, which draws from a tiny pool of very tall athletes.

I will grant that NBA players would likely win most of the time in javelin, shotput, and discus. But I see top soccer players as having the advantage in most other decathlon events, with a couple of them probable toss-ups (pole vault and maybe high jump). Elite soccer players are incredibly athletic, even if most American sports fans haven't noticed.