I can tell his face is very low detail. When that's the case, we can use more detailed previous and follow up panels for clarification, as well as other indicators beside the face.
Previous panels show X Drake in base.
Immediate follow up panel going close up on his and Zoro's face's show his human form face.
Other details beside the unclear face all fight his human form and not his hybrid form.
You have either all of these combined, or a contrived explanation about how he went and transformed only certain parts of his body that we can't really see be transformed, but maybe we asume they are transformed, except for the parts that we can see are not transformed, in order to say that his low detail face is meant to be closer to his hybrid form face and not his human form face ? All in that one low detail panel that goes against previous or follow up panels.
Ain't that a bit crazy