The differences between SSP and DSP are of various kinds, as seen in section 2.2.
switching from surface to deep syntax leads to higher gain for predicted data than for gold data: 5.1 points (56.7 to 61.7) for all trigger, instead of 4.2 for gold data and 6.7 points (61.3 to 68) instead of 6.4 on gold data for verbal triggers.