On December 30 The Atlantic posted this article by Christopher Caen (son of famous San Francisco writer Herb Caen) about top-two systems. The article is balanced. However, it has factual errors. It says that before used the top-two system, independents could not vote in primaries. This is incorrect. Both the Democratic and Republican Parties allowed independents to vote in their primaries (for all office covered by the top-two system) in the decade before the top-two system went into effect. For proof, see this page on the California Secretary of State web page.
The article also says that California State Senator Steve Glazer would not have won under the system in place before top-two. But before California used top-two, it used a blanket primary for all special congressional and legislative elections. Glazer was elected in a special election in 2015. He easily polled more votes in the first round than any other Democrat running, so under the old blanket primary rules, he would have been the only Democrat in the run-off and he easily would have beat his Republican opponent.
The article also focuses on Abel Maldonado, without noting the irony that in Maldonado’s many runs for partisan office, he always won in his home area counties of San Luis Obispo and Santa Barbara counties, until he had to run in a top-two election. That election was for Congress in 2012, and he lost those two counties to Lois Capps, the incumbent Democratic member of Congress.
The article does not say anything about how California’s turnout has plummeted under top-two. California voter turnout declined more between November 2010 and November 2014 than any other state. The article says nothing about findings of political science research that the top-two system does not elect more moderate candidates. For example, see the exhuastively researched paper by Eric McGhee, Seth Masket, Boris Shor, Steven Rogers, and Nolan McCarty titled “A Primary Cause of Partisanship? Nominations Systems and Legislator Ideology.” It is in the American Journal of Political Science.