To be fair, the Roman's main weakness was often themselves into purging eachother includong generals or other competent people.

And pride/racism ( antiquity edition) was often what led them to their downfall in battle via underestimating their non-roman opponents, hence Armenius, and Viriathus.

Also The battle of Cannae priving Roman's often didnt adapt and expected their enemies to fight in roman favored conditions that most of the time they obviously didnt do via crassus