My own A99-D600 ISO test

Nope, you are looking at DXO's measured ISO ratings.  The scores they post are using the measured ISO, not manufacturer's ISO, that meet a very specific requirement in dynamic range, SNR, and color depth that DXO has set.  The OP here is giving their results based on the manufacturer's ISO.

If you convert the measured ISO list in the sports score to manufacturer's ISO, it would be around 3982 for the D600 and 2726 for the A99.  Rounded to the nearest 1/3 stop, this would be ISO 2500 if rounded down (ISO 3200 if rounded up) for the A99 and ISO 4000 for the D600.  If based on the rounding, it is equivalent to about 1/3-2/3 stops difference in favor of the D600.  If looking at the actual numbers themselves, it is probably closer to about a 1/2 stop difference (but ISO speeds are rarely ever measured in 1/2 stops).

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Paul