Scoured the internet and forums on Yoslan Herrera. During his last stint in the majors (2008) he was a starter who only topped out at the mid-high 80s with a good breaking ball.
http://www.altoonamirror.com/page/blogs.detail/display/5994/Remember-Yoslan-Herrera--Believe-it-or-not--he-s-back-in-the-majors.html
"Herrera always had a sharp curveball during his Curve days, but with a fastball only in the mid- to upper-80s, the right-hander couldn't get by much on that and had to rely heavily on his offspeed stuff. That's almost always a bad sign for a minor league pitcher, and it was especially bad for the Pirates, who had given him a three-year contract worth $1.9 million but never got much in return."
As the article stated, Herrera couldn't get it done by just throwing the breaking ball to cover up his lack of velocity. Well in his debut with the Angels he topped out at 97 miles per hour and continued to show a sharp breaking ball. Maybe the increased velocity can be the ingredient that gets his career on track. Just trying to be an optimist.