Some fans and writers have been insisting for four years that Hendricks doesn't throw hard enough to be a really good starting pitcher. Each year he has shown they were wrong (though he did have a sub-par year in 2015), they predict that his success won't last, because he doesn't throw hard enough.
Here is what he's done each of four years in the major leagues:
2014: 2.46 ERA, 154 ERA+, 1.083 WHIP, 2.9 WAR
2015: 3.95 ERA, 96 ERA+, 1.161 WHIP, 1.8 WAR
2016: 2.13 ERA (#1 in NL), 196 ERA+(#1 in NL), 0.979 WHIP, 5 WAR
2017: 3.03 ERA, 144 ERA+, 1.189 WHIP, 3.5 WAR
It remains to be seen how long Hendricks will remain to be one of the better starting pitchers in baseball (which by some measures I gather he has been the last couple of years). But I do wonder what it will take for him to earn the respect he's earned with his actual performance.