How did Hogan and Baker do last year? Christie in 2013? Kasich in 2014? Doubt any actually won it but they all definitely did better than the average Republican.
I'd imagine that all four of them got into the teens, possibly doing as well as Nixon and Ford did back in the 1970s (around 16-18% or so), maybe a few points less than that. Hogan, in particular, managed to garner more than a quarter of the vote in heavily black (and heavily Democratic) Prince George's County and Baltimore City, doing significantly better in those counties than he did in 2014. And given that Baker actually won Suffolk County, and managed to get around 43% in Ayanna Pressley's district, it's obvious that he won a substantial number of nonwhite voters, including blacks. Christie too, got close to 40% in Essex and Hudson Counties, which have heavy concentrations of black voters. And Kasich won Cuyahoga and Franklin Counties, and only lost Joyce Beatty's congressional district by a few percentage points.