On page 110 in All the Verbal, it is said that "Official GMAT questions have required that this new-copy usage of that or those agree in number with the previous version."
Then the incorrect example is provided "The company's digital watch offering is outperforming those of its competitors".
To clarify, is this incorrect because those is plural but the antecedent is singular? Is that all that this is trying to say? Thank you.