Ramirez was 1-5 with a 4.06 ERA in 13 starts for Seattle this season over five stints with the club, as he's split the season between the Mariners and Rainiers. The 24-year-old had a 1.15 ERA with 25 strikeouts in 31 1/3 innings over his last six starts in the Majors, though he's given up 23 hits and 19 walks in that stretch.
Ramirez opened the season as the Mariners' No. 2 starter with Hisashi Iwakuma on the disabled list and Chris Young and Roenis Elias still unknown commodities. He won his opener against the Angels on April 1 with seven innings of two-run ball, but hasn't had a big league victory since.
The Nicaraguan native pitched well recently in Tacoma, going 5-2 with a 3.12 ERA his last 10 starts and 3-1 with a 2.28 ERA in four August outings.
"I've seen a lot of growth," manager Lloyd McClendon said. "The command of the fastball is a lot better, his secondary stuff is more crisp. I don't think he's pitching away from bats any more. He's making quality pitches with two strikes. He's come a long way. This is a very deserving opportunity for him."
Ramirez's spot start, combined with Thursday's off-day, allows the rest of the rotation to get an extra two days of rest before their next starts and the start of the September stretch run.
"This move was made more because of what he's done and how he's pitched at Triple-A," McClendon said. "It afforded us the opportunity to back the other guys up. I'm really happy for him. I think he's come a long way."
McClendon didn't rule out a scenario in which Ramirez could remain in the rotation going forward if he pitches well.
"That's very possible. Absolutely," he said. "I would say it's Plan B. It's definitely in effect. We'll see how things go. But it's a definite option and one we'd be very comfortable with."
Paxton will remain in the rotation and slide right back in when he's recalled next week. The 25-year-old has been outstanding when healthy, and he threw 6 2/3 scoreless innings in a 5-0 victory over the Rangers on Tuesday. Paxton is now 7-1 with a 1.71 ERA in 11 career starts, and 4-1 with a 1.83 ERA in seven outings this season.
The only other Major League pitchers to debut since 1944 with at least seven wins and an ERA lower than Paxton's 1.71 mark in their first 11 career starts were Steve Rogers (7-3, 1.28 ERA in 1973 with the Expos) and Phil Niekro (8-3, 1.20 ERA in 1967 with the Braves).