The Royals acquired two young starting pitchers Wednesday from Pittsburgh in exchange for right-hander Vin Mazzaro and first baseman/designated hitter Clint Robinson.
Mazzaro and Robinson were designated for assignment last week, which signaled the Royals saw neither one as part of the club’s future.
Catcher Brayan Peña and right-handed pitcher Chris Volstad, who were also designated for assignment, chose to become free agents rather than accept outright assignments to the minors after clearing waivers.
The trade with Pittsburgh returned right-hander Luis Santos, 21, and lefty Luis Rico, who turns 19 on Thursday. Both pitched last season in the Dominican Summer League and were assigned to the Rookie Surprise roster.
Santos was 6-3 with a 2.44 ERA in 14 games in the Dominican, while striking out 74 in 62 2/3 innings and holding opponents to a .184 average. Rico was 0-1 with a 7.04 ERA in nine starts.
Mazzaro, 26, never evolved into the reliable rotation arm the Royals envisioned when they obtained him with minor-league lefty Justin Marks in a Nov. 10, 2010 trade from Oakland for outfielder David DeJesus. Mazzaro was a combined 5-4 with a 6.72 ERA over the last two seasons in 25 big-league appearances, including 10 starts. He spent much of his time at Class AAA Omaha.
Robinson, 27, put up big minor-league numbers in recent seasons but was blocked at the major-league level by first baseman Eric Hosmer and designated hitter Billy Butler. Robinson was hitless last season in four big-league at-bats.
Peña, 30, spent much of the last four seasons as the club’s backup catcher but batted just .236 last season with two homers and 25 RBIs in 62 games. His spot became at risk when the Royals claimed Brett Hayes on waivers from Miami.
The Royals acquired Volstad in an Oct. 26 waiver claim from the Chicago Cubs but deemed him expendable after acquiring Ervin Santana in a trade from the Angels and retaining free-agent Jeremy Guthrie.
Peña, Mazzaro, Robinson and Volstad were among seven players designated for assignment on Nov. 20, which provided the Royals with a 10-day window to trade them, release then or send them through waivers.
The others were pitchers Ryan Verdugo, catcher Adam Moore and outfielder Derrick Robinson.