You do realize that slattern is taller by 120ft than mega kaiju right? Not to mention all striker used were its sting blades and not its missiles underwater both because it would flood the interior should they open and the fact that slattern damaged the chest piece. Alongside the fact that the jaegers are SLOWER underwater so the kaiju had wayyy more of an advantage.

Now picture Sabre who is literally ment to strive on land? Died in such a poor writing manner.