Beltran doubled home two runs in both the first and second frames to key the early assault. Six of the St. Louis runs came in the second inning, during which David Freese and Tyler Green both had two-run doubles.
Joe Kelly (1-0) benefited from a 17-hit attack to record his first major league win with a six-inning effort. He gave up three runs without a walk in his third career start.
Kansas City starter Vin Mazzaro (3-2) was roughed up for six hits and seven runs while retiring only four batters.
The Cardinals' Matt Carpenter returned after spending more than a month on the disabled list and was one of five St. Louis batters with at least two hits.