Yes I think Ngannou is the more polished striker. He outstruck a higher caliber of fighters than Tai.
Yes Gane is a superior grappler. He can get a takedown and he can submit people. Tai doesnt do either. And in fact Tai has been grapple fucked, ground and pounded out and submitted.
Tai can and should go all ape like Ngannou against Rozenstruick. Yeah it looks ugly but it works. Otherwise Gane can circle all night and hit him, evade, repeat.