Although reliever Danny Farquhar ultimately took the loss after giving up a pair of runs in the eighth, Seattle's 5-8 start clearly can be laid at the feet of a rotation that has gone 2-5 with a 5.58 ERA in the first 13 games.
"Obviously, when you don't pitch well, that's a reason to be concerned," said manager Lloyd McClendon. "I'd be lying if I said I wasn't concerned about it. We've got to get it straightened out, because we're much better than we've shown to this point. When you score five runs in a game, you should win a ballgame."
A year ago, the Mariners were 67-12 when scoring four or more runs, thanks to a pitching staff that had the lowest ERA in the American League at 3.17. This season they're just 4-3 when scoring four-plus runs, the team ERA is near the bottom of baseball's 30 teams at 4.65 and the starters have completed seven innings just three times, with two of those outings from ace Felix Hernandez.
Tom Wilhelmsen often bridged the gap in short starts last season, but the big right-hander is on the 15-day disabled list with a hyperextended elbow, and the bullpen hasn't been as stable as a year ago either. Yoervis Medina couldn't protect the two-run lead he inherited when McClendon pulled Iwakuma after just 71 pitches following a one-out double in the sixth, and Farquhar wound up taking the loss when Luis Valbuena hit his second homer of the game in the eighth.
Iwakuma has been a rotation anchor the past two and a half years, one of the more underrated right-handers in the game and an AL All-Star in 2013, but his ERA is 6.61 after three outings and McClendon gave him the early hook even with a lead.
"He just wasn't throwing very good," McClendon said. "I tried to turn it over to the bullpen and see if we could hold it and win a ballgame."
Iwakuma left a pair of two-seam fastballs up in the zone and surrendered solo home runs to Valbuena and Colby Rasmus, eventually departing with four runs in 5 1/3 innings. He's allowed five home runs in 16 1/3 innings over his three starts.
"I actually feel pretty good on the mound," Iwakuma said through translator Antony Suzuki. "Even today, I felt like my stuff was working. Just some of the pitches that were up in the zone, they didn't miss, and that kind of hurt."
Iwakuma said that his slider was better after having trouble with that pitch in his previous outing, against the Dodgers, but now he needs to get his two-seam fastball down.
"I feel like I'm getting better and closer," he said. "I feel bad, because the team is scoring a lot of runs and I'm not doing my job. So that's the first thing I need to do. I need to win for myself as well, and that's why I look forward to my next start."
McClendon is looking forward to all of his starters going deeper into games and pitching with more consistency. He said wear and tear on his relievers is inevitable if he keeps needing to use half of his bullpen each game.
"I love my bullpen, but if we keep running them out there, they're not going to be worth a darn," he said. "I have to find a way to rest them. That's not going to work for an entire season. We need to get consistent starts and more days off [for the relievers] right now."