Some feel he's among the, if not the hardest hitting FW of all time. "A feather who hit like a MW", for whatever thats worth. Beat Young Corbett II, the man who twice beat Terry McGovern. McGovern himself got Herrera out of there too. Interesting to note that Herrera was a advocate of the Ketchel training regimen... Cigarettes and booze.
First fighter of Mexican descent that i know of, and also an amazing Knockout record, especially for that era. When even the biggest punchers didnt have ko% like him, outside of Stanley Ketchel who came after.