Baseball America's John Manuel reports. Some relevant clips:
Herrera, 25, has finalized a deal on a major league contract with the Pirates, though the deal is not official pending Herrera passing a physical. . . .
Herrera has had success in Cuba, with a career 18-7, 3.72 record. Pirates general manager Dave Littlefield said nothing was official with Herrera, though [his agent Jaime] Torres said the physical is the only legal obstacle to the signing. He confirmed the organization's interest in Herrera, saying the Pirates have "seen him a few times in the Dominican. I know there's interest from other clubs. I just don't want to comment until it's really official."
The 6-foot-2, 200-pound righthander, who is still working out in Santo Domingo in the Dominican, has shown command of a fringy fastball and what Torres termed an above-average curveball, and one scout liked him a lot.
"He's got an above-average split-finger (fastball) and was 88-92," the scout said after seeing Herrera pitch in a workout in August. "I could see his velocity jumping up to 90-94 once he gets into a system and he could very easily be a No. 4 starter in the big leagues."