Hisashi Iwakuma is the most efficient pitcher in baseball by the numbers, with so few walks that Seattle Mariners manager Lloyd McClendon could only joke about his bewilderment when Iwakuma issued one in his last outing.
The only time the right-hander has run into serious trouble over the last month came against the Baltimore Orioles, whom he'll face again Sunday in the finale of this three-game set at Camden Yards.
Iwakuma (9-5, 3.06 ERA) has pitched at least seven innings in five straight starts and is 4-1 with a 2.32 ERA over his last six. He has 39 strikeouts to only one walk during that stretch, issuing it Tuesday while giving up two runs in seven innings to beat Cleveland in a 5-2 win.
The walk - just his ninth in 117 2-3 innings this season - snapped Iwakuma's streak of 139 consecutive batters faced without allowing a base on balls. The right-hander's 10.44 strikeout-to-walk ratio is the best in the majors, and his 13.5 pitches per inning are the fewest of any starter in baseball.
"I'm a little disappointed he walked a batter," McClendon said sarcastically. "He's pretty good. He did a nice job for us. He doesn't mess around."
Iwakuma's only loss over his six-start run came July 24 against Baltimore, allowing four runs - all in the third, including a three-run homer by Delmon Young - in seven innings of a 4-0 defeat.
He'll try to avenge that loss as he opposes Chris Tillman, who looks to maintain a perfect record against Seattle (57-53).
Tillman (7-5, 3.97) saw his ERA hit a season-worst 5.20 on June 5, but he's since dropped it significantly while going 2-1 with a 2.60 ERA over his last eight outings.
He didn't have his best stuff Tuesday, though, giving up five runs - three earned - in five innings of a 7-6 victory over the Los Angeles Angels in 12. That was arguably the worst performance he's had at home, where Tillman is 1-5 despite a 3.10 ERA.
The right-hander has won each of his five career starts against the Mariners with a 2.45 ERA, up from the 0.98 mark he posted through the first four after giving up six runs in 5 1-3 innings of an 11-8 victory Aug. 2, 2013.
Tillman hasn't had much success against Robinson Cano, who is 11 for 25 with two homers and a double lifetime in the matchup. Cano hit a three-run homer in the Mariners' 6-3 victory Sunday, equaling his RBI total from his previous 14 games combined.
Dustin Ackley went 3 for 5 with a solo shot for Seattle, which will be seeking back-to-back wins for the first time since beating Oakland on July 11 and 12.
"We don't have the big bopper in the middle of our lineup, obviously, but we've got some guys that are professional hitters and know the strike zone and know what they can do up there," McClendon said.
Manny Machado is 6 for 9 in the series for the Orioles (61-48) and is batting .379 over his last six. Chris Davis didn't start due to a stomach virus for Baltimore, which leads Toronto by 2 1/2 games atop the AL East.
Seattle placed Corey Hart on the disabled list Sunday with a bruised right knee. He missed the entire 2013 season after having surgery on the same knee.