I am not a EE, but that's a 12 bit ADC, so if you aren't using the receive equalization feature, aren't you limited to about 72dB just due to quantization?
That makes sense; the total noise power is spread across the entire Nyquist bandwidth of the ADC, which is 2GHz in this case. I haven't ever worked with ADCs with such a large ratio of sampling rate to band-of-interest before, so it was mildly surprising to see 10s of dB of processing gain.