So if 2018, 2016 and 2015 won that's 3 out of 7 not bad. What about the 2017,2014 and 2013?
Apparently, there is some confusion on the All-American results site with game numbers in some of the semifinals and finals.
In summary, the Top Guns web site is calling out the following final results :
2014 Black All American Showcase Champions 2014 Purple All American Showcase Finalists 2015 Black All American Showcase Champions 2016 Black All American Showcase Champions 2017 Black All American Showcase Finalists 2018 Black All American Showcase Champions