Looking for a prospect with serious helium potential? See Rangers righthander Roman Mendez.

Mendez, 21, allowed only one run (unearned) in six innings tonight for high Class A Myrtle Beach, striking out nine of the 21 batters he faced with no walks and three hits allowed. 

The Rangers have baseball's best farm system thanks largely to the work of their international scouting department, but the Dominican-born Mendez came to the organization at the 2010 trade deadline as the main player in the deal that sent Jarrod Saltalamacchia to the Red Sox. We wrote about Mendez first when he signed with the Red Sox for $125,000 in July 2007 and then tabbed him as one of the top prospects in the Dominican Summer League after his debut season in 2008, when he pitched well at age 17 and showed good command of an 89-91 mph fastball that touched 93.

His velocity has blown up since then, and he drew the attention of scouts last month at big league camp, where he pitched well and sat in the mid-90s with his fastball in short stints. He can reach even higher than that, though he'll sit in a lower range as a starter, and he's stood out from his peers since he was still in the Dominican Republic for his ability to throw strikes. Mendez is the No. 20 prospect in the Rangers' organization right now, but he's the kind of guy who could take a big leap forward this season.