I agree.
It is noteworthy that both of them have <50% success in shorter rallies and generally do better as the rallies go on (more so for Kei).
Put briefly, both of them essentially have both too weak serves and returns for their level and games. Which sucks for them, seeing as shorter points make up the bulk of tennis matches. The very best players may differ somewhat in how much their strength is toward serving or returning, but what they all have in common, even the supposedly 'defensive ones', is that they do very well in the all-important shorter rally categories (1-3 and 4-6).
Notice especially the great myth of the pusher Andy Murray, who in reality relies the most on his success in shorter rallies.
It is very interesting to me that Kei outdoes pretty much all of these guys in the extended rallies. But they all crush him between 1–6 shots.