The 2013 American League All-Star went 15-9 with a 3.52 ERA in 28 starts last season and his WHIP was fourth best in the American League at 1.050. But Iwakuma's WHIP is 1.408 in his first three starts and he's given up five homers in 16 1/3 innings.
McClendon said Iwakuma's early issues are being overanalyzed, along with much of Seattle's struggles, as a club projected as a strong playoff contender got off to a 5-8 start.
"Iwakuma is not as sharp as he's going to be," McClendon said. "He'll get better and he'll get things straightened out. But I will point this out and this is real important: During the course of a season, there'll be a stretch of 13-15 games where we play three or four games under .500. But when it happens at the beginning of the season, you have nothing to compare it to and everything is blown out of proportion.
"We have to keep our perspective and our heads about us and realize we haven't even played a tenth of the season. We're 5-8 and everybody is panicking and Iwakuma's not throwing good. He's going to throw good. He's going to be just fine. We need to get things straightened out and we have the type of team, when we do get things straightened out, we'll get on a real good roll. And it'll be a lot of fun. Just be patient. I promise you it'll get straightened out."
McClendon said he wouldn't publicly discuss what Iwakuma needs to work on to get back on track, but said adjustments are being made after looking at film. While the 33-year-old's fastball has been a few mph slower than normal in his initial starts, the manager said that wasn't the problem.
"I'm not overly concerned with the velocity," McClendon said. "I'm more concerned with command than velocity. He's leaving too many balls in the middle of the plate and working behind on too many hitters and that's what we've got to get straightened out. The velocity for Iwakuma will come."
Iwakuma said he thought he took a step forward in Monday's outing, other than two fastballs he left up that were hit for home runs.
"I'm feeling better and better each start," he said through translator Antony Suzuki. "Last time [the Dodgers] hit my slider pretty well, so I wanted to work on that and keep it down and sharp. I was able to do that, but my two-seamers were both high so I have to work on that as well."
Iwakuma's next start will come Sunday against the Twins in the final game of the current homestand.
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.