As I read the opinion I was struck at the number of times the decision pointed out the differences between sec 5 and sec 2 so they could come to their conclusions. That may also be something that gives SCOTUS pause. I also found the dissent on CD 25 far more compelling than the majority from a methodological viewpoint.
This is the type of evidence used by that opinion:
Representative Dukes provided specific examples of elections to support her analysis of minority groups’ voting power in CD 25. She recalled the 2008 election for Travis County Tax Assessor, in which the African-American supported by the coalition successfully defeated, with 74% of the vote, an Anglo male “progressive Democrat.”
Nelda Wells Spears was the tax assessor-collector for nearly 20 years. In Texas, it is traditional to write the checks for taxes to the name of the county tax assessor, with or without their title, so:
"Nelda Spears" or "Nelda Spears Travis County Tax Assessor" rather than "Travis County" or "Travis County Tax Assessor". Vehicle registration in Texas is handled by the counties, so that anyone who owned a home or a car in Travis County had likely written a check to the office. So the incumbent has higher name recognition than you would otherwise expect for the office.
She was facing Glen Maxey, the first openly gay Texas legislator, who was recently elected as the LGBT member of the DNC. In Texas, the Tax Assessor-Collector is also the voter registrar (a legacy of when the the office collected the poll tax). Maxey felt it was the key job of the office to lobby the legislature on voter registration and other matters, rather than run a professional office that handles millions of dollars and 100s of 1000s of transactions.
In the 2008 primary, Dukes herself was challenged as being a Craddick D, a Democrat who had been appointed a committee chair and supported Craddick. I think she was the only Craddick D who survived a primary challenge, and she did so by emphasizing that he did was what was in the best interest of her (Black) constituents, rather than kowtowing to the Democratic party elite (in a 79% Obama district).
Spears herself carried every precinct in Travis County, but a tiny one that Maxey carried on a 1:0 vote, and he managed to get above 40% in just a few precincts. Because Spears was above 90% in some precincts vs 74% countywide, does that prove Blacks are essential to victory of a Democrat, or simply that they are even more likely to vote for a long-time county incumbent who is Black, particularly when they may feel that the Democratic elite are trying to knock off their representative in the same primary, than other voters.
Spears retired in 2011, and in the 2012 primary endorsed a long time deputy, serving as his campaign treasurer. Spears endorses Wilson
He lost with 25% of the vote to an Anglo male. There was more of a mix of results. While Wilson did not win any precincts with 90% of the vote, he did win some with substantial majorities.
The 2008 race was coincident with the presidential primary, which had 4.4 times as many votes (Obama carried Travis County with 63%, while losing statewide to Clinton).