Is Hearts more powerful than Merged Zamasu?

Hearts is the leader of the Core Area warriors which should mean that he's the strongest of them, he was also able of effortlessly counter Hit's timeskip whereas Hit was able of holding his own for a short time and of landing a hit on Cyborg Merged Zamazu in the manga.

Hearts should stomp. He managed to hold down Jiren and SSBE Vegeta completely and transformed the latter back to base. Jiren was beating the crap out of Merged Zamasu, only reason he remained in the fight was because he's immortal.