If true, this would be bad news. But such a conclusion is far from certain. In order to judge Mr. Yeats's work, it is first necessary to establish the criteria by which to judge any trade policy. As a rule of thumb, governments should take every opportunity to open markets. Trade barriers restrict the freedom of individuals to exchange their own property with citizens of other countries.
Tariffs are taxes that punish individuals for making choices of which their governments disapprove.
Further, economic liberty is the only known path to growing productivity, prosperity and good-paying jobs. Thus all trade liberalization, like all tax cuts, should be applauded. Critics of Mercosur must show that it is a faux free-trade zone that reduces net liberty by increasing the cost of importing goods from other countries, and thus harms consumers within Mercosur. Mr. Yeats certainly does not succeed in doing this. But Mr. Yeats ignores other reasons for shifting exports.