Top prospect Taijuan Walker could've made the start had he not developed shoulder issues as well. Walker was shut down during a rehab start on Tuesday with tightness. The only other pitcher at Triple-A Tacoma on the 40-man roster is Anthony Fernandez, who pitched on Wednesday.
Asked whether Maurer was getting the nod because there weren't any other options, McClendon didn't think so.
"I think he's probably deserving," McClendon said. "He was in consideration during Spring Training to make this club. I think he deserves the opportunity."
The 23-year-old went 5-8 with a 6.30 ERA in 22 games (14 starts) in 2013, his first season in the big leagues.
Maurer has posted a 0-0 record and a 2.16 ERA in four outings (one start) for Tacoma. He is rebuilding his arm strength after a back injury limited him during the spring. Maurer has pitched just 8 1/3 innings.
"I think he's on a pitch count," McClendon said. "I don't want to say what it is. I don't want the opposition to know what it is, but he's like anybody else. We need to watch what he does out here."
Christina De Nicola is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.