"Just more than anything, he's working on a couple things with Edgar and I wanted to give him an extra day to just clear his mind and go from there," said Servais, who went with backup Jesus Sucre for a second straight day in Sunday's series finale with the Astros. "He got a little fatigued at the end of the first half and I thought the four days would help, but it's more of a mental break than anything.
Servais said Iannetta's intense demeanor works against him when he starts pressing.
"He's very hard on himself," Servais said. "Of all our guys, he certainly takes it to heart more than anybody. The wins and losses, his performance, defensively, offensively, there's only so much you can do every day. It's a tough job back there, it really is."
The Mariners have Mike Zunino waiting in the wings in Tacoma, but they are going for now with Sucre, who was activated off the 60-day disabled list on July 6 after recovering from a broken leg.
• Right fielder Nelson Cruz (bruised left foot) and shortstop Ketel Marte (sprained right ankle) were both back in the lineup on Sunday after sitting out one game with minor issues.
• Reliever Charlie Furbush threw a perfect seventh inning in Triple-A Tacoma's 7-2 win over Colorado Springs on Saturday in his fourth rehab appearance as he works back from a year's absence with shoulder issues, but "he's still a ways away," Servais said.
• Norichika Aoki went 4-for-4 in Tacoma's win and the 33-year-old outfielder has hit .352 with a .438 on-base percentage in 14 games since being sent down.
"He's doing well," Servais said. "We are noticing."
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.