In an effort to boost a rotation that had MLB’s worst ERA last season the Orioles brought in a pair of starters who’d thrived in Japan, signing Wei-Yin Chen for $11.3 million and Tsuyoshi Wada for $8.15 million.

Wada experienced elbow problems early in spring training and will miss the entire season following Tommy John surgery, but Chen is looking like an excellent investment so far.

Last night he tossed seven innings of two-run ball against the Yankees, out-dueling CC Sabathia and improving to 4-0 with a 2.45 ERA in seven starts. His secondary numbers aren’t quite as impressive with a modest 32/14 K/BB ratio in 44 innings, but Chen has allowed just three homers and has proven very capable of success against strong lineups.

Of those seven starts two have come against the Yankees and he’s faced the Rangers and Red Sox once apiece. Those are the three highest-scoring teams in the American League and the 26-year-old left-hander has a 2.84 ERA against them despite averaging just 90.1 miles per hour with his fastball.