My point is that for WvA, road racing was much more of a side job until 2018, than for MvdP, who combined everything but already put more focus on the road, at a younger age.
MvdP already had 2013, 2014 and 2015 seasons with around 3000K and 20 race days
WvA had 2013, 2014 and 2015 seasons with around 1500K and 10 race days.
So by the time WvA had a +3000K season and 20 racedays in 2016, MvdP already did that for 3 years (and became WC juniors on the road,...).
MvdP had more road pedigree at a younger age, and with this perspective, it makes sense that WvA had more potential for improvement on the road, at a later age, as he started later, than MvdP.