You know you can be serious and training to get better at something ? lol. Nothing in this chapter suggest Zoro didn't put power in his DD
It suggest that he training his CoC on his named attack.
As Zoro said when he is using bandana, it's always serious him.
Not me who said that but Oda and Zoro. Lol
Which could be weaker version of DD.
Kinda like Luffy weaker version while using G4 on base.
HELL DD that he used probably his all out Haki lol, cuz we've seen that type of trail on Roger or WB
In the end he will get stronger named attack or version than DD