When the attention of the Type 4 Mutant Beasts was on the zombie horde, every single action of theirs caused the surrounding zombies to be flattened into meat paste. With every passing second, there were over thousands of zombies being taken out of commission. That was the problem with the zombies, their densely packed formation caused them to suffer as an entire bunch.
Yue Zhong had no way of killing over tens of thousands of zombies in one blow, but the 7 Type 4 Mutant Beasts could easily trample over them as long as they were willing to.
With the 7 behemoths lured away, 300-over L4s, a thousand over S4s, and 500 Devourers led a huge horde of Type 2 & 3 zombies numbering at least in the dozens of thousands out from one shelter.
This huge horde that could easily decimate any human troops quickly reached the centre of the sea warriors, and began their clash against the Mutant Beasts.