First of all, as the article and the link on which it is based grudgingly admit, the relationship between the unionisation of teachers and performance in standarized testing proves nothing at all, not simply because - contrary to the indoctrination in those schools about global warming and other leftist pieties - correlation is not causation. However, another obvious objection is that the ACT and SAT tests are set by the teachers themselves in an institutional act of begging the question.
Yet another point ignored by the article is that the reason Republican are hostile to state employee trades unions is that the unions are the mainstay of the Democrats, recycling tax money back to the party that, unsurprisingly, has increased their pay and benefits beyond the ability of the productive sector to sustain them. So the following conclusion, so "wet" and so obviously written with an eye back across the Atlantic that it must have been by a Brit, is farcical.
There are clearly some serious problems facing American governance , and public-sector unions are going to have to make adjustments  to solve those problems, whether it means pension restructuring or allowing the firing of incompetent teachers. But those kinds of reforms will be unachievable if unions correctly  understand that their opponents, including Scott Walker and the modern Republican Party, are not in fact interested in collaborating with them on solutions , and are instead trying to destroy their existence as institutions .
- No shit. Do you suppose a bloated parasitic sector might be one of them?
- Adjustments, eh? Not "savage cuts", evidently.
- There can be no "if" in that statement. The unions' understanding is "correct", therefore their opponents are wrong, therefore:
- Collaborative reforms are unachievable by Republicans [UK Conservatives] and we must all vote Democrat [UK Labour].
- As to the Republicans attacking the unions, as the French aphorism puts it: Cet animal est très méchant: Quand on l'attaque, il se défend [This beast is very wicked: It will fight back, when it’s attacked].