SEATTLE -- The decision to bring right-hander Brandon Maurer back from Triple-A seemed like a curious one when the Seattle Mariners announced the news Wednesday afternoon.

However, with the team off Thursday and with right-hander Taijuan Walker ready to make his season debut, the move made all the sense in the world.

Maurer, who struggled mightily as a starter with the Mariners earlier this season, will work out of the Seattle bullpen until there is a need for a fifth starter -- presumably, Monday night in Houston.

The Mariners optioned right-hander Erasmo Ramirez to Triple-A Tacoma despite a four-game stretch that saw the 24-year-old starter allow just two total runs. Ramirez struggled with his control and was never considered a long-term part of the rotation, and the demotion was more about Walker's readiness than anything Ramirez did in recent starts.

Walker, the Mariners' top prospect, arrived at spring training with shoulder discomfort before winding up in the minors -- first on a rehab stint, then after being optioned to Triple-A earlier this month. He could make his 2014 Mariners debut Monday night.

Walker has been a top prospect in the organization for the better part of two years, and his cup of coffee with the Mariners late last season did nothing to disappoint. He went 1-0 with a 3.60 ERA in three starts. Walker got off to a slow start at Triple-A this year but gradually built up his innings. After throwing a four-hit shutout Tuesday night, Walker looked ready to return to the big leagues. He is 2-1 with a 4.11 ERA in six starts for Tacoma.

Almost as intriguing is the sudden emergence of Maurer as a relief pitcher. The converted starter came out of the bullpen Wednesday night throwing a 99 mph fastball. He struck out four of the seven batters he faced while completing two scoreless innings.