Martinez, 21, was a consensus Top 40 prospect among Baseball America (No. 38), MLB.com's Jonathan Mayo (No. 33) and ESPN's Keith Law (No. 39). The Dominican native has totaled just 83 innings at Double-A and has a 2.82 ERA, 7.3 K/9 and 2.5 BB/9 in 17 starts. In total, he has 277 strikeouts in 259 2/3 minor league innings.
Baseball America, Law and Mayo all praise Martinez's fastball, which sits at 94-98 mph and can be dialed up to 100 when he needs it. Martinez's curveball draws more praise than his changeup, though BA notes that the changeup could develop into a third plus pitch for him. Mayo adds that it's a circle change with nice fade, and he doesn't feel it's that far behind Martinez's sharp 12-to-6 curveball.
Martinez is listed at 6'0" and 185 pounds. In addition to eliciting comparisons to Pedro Martinez (no pressure, Carlos), his size has led many to question whether or not he will be durable enough to handle a starter's workload. Martinez already missed a month with shoulder tendinitis last season but was able to bounce back. In his write-up, Law noted: "If the shoulder issue recurs, he may end up a shutdown reliever with two pitches near the top of the 20-80 scale." Upon learning of Martinez's promotion, Baseball America's J.J. Cooper wondered whether or not Martinez would ever start again, given the Cardinals' bounty of talented starters (Twitter link).
The Cardinals have kept Martinez in the minor leagues long enough to delay his free agency by a season, but his call-up falls well short of the June barrier that would prevent him from becoming a Super Two player. If he sticks on the roster from this point forward, Martinez will pick up 150 days of Major League service time and be under team control through the 2019 season.