BALTIMORE, MAY 30 -- On another warm, muggy night, Mike Morgan and the Seattle Mariners were all over the Baltimore Orioles again.

Morgan was on their fists with fastballs and at the corner with sliders and up high with a tantalizingly slow curveball. The result was an efficient seven-hitter and a 12-0 Seattle victory before 28,874 at Memorial Stadium.

He had plenty of help as the Mariners totaled 15 hits off four Orioles pitchers, including two homers and three RBI from third baseman Jim Presley and a home run and three RBI from catcher Dave Valle.

The loss was the second in a row for the Orioles (26-22), a team that hadn't dropped back-to-back games since early May. It was only their third loss in 13 games, and all three have been to the Mariners -- two on complete games by Morgan.

"Morgan was outstanding," Orioles third baseman Ray Knight said. "He threw a lot of breaking balls, and at two different speeds. He'd just show you the fastball now and then. His best pitch was the breaking ball, and he'd run one in, then throw another away. You have to give him credit."

A team with no worries three days ago, the Orioles now have several, the main one a pitching staff that hasn't gotten six innings out of a starter in 10 straight games. Worse, early exits by the starters are taking a toll on the bullpen.

The Orioles have needed fewer than three pitchers only once in their last 10 games and four or more six times.

Tonight, rookie Eric Bell (5-2) allowed the Mariners six hits and four earned runs in 5 1/3 innings. He was behind 2-0 in the fourth after Valle and Presley hit back-to-back homers, and his evening got worse.

The Mariners led 2-0 after four innings, 7-0 after six and 10-0 after seven.

"Sometimes you just get the heck beat out of you," said Orioles Manager Cal Ripken Sr. "It didn't matter what we threw. They hit it over the fence, off the fence, blooped them, hit them between the infielders and between the outfielders."

In Seattle's clubhouse, Manager Dick Williams was almost giddy after watching his team's first shutout of the season as the Mariners improved to 25-23 -- their best start in history -- and remained 3 1/2 games behind Kansas City in the American League West.

"Excellent," he said. "{Morgan} battled his rear end off, and it's tough to concentrate all the way in this kind of game. He really kept them off balance."

Morgan (5-5) became the third pitcher to shut out the Orioles this season, the first right-hander. The others were by Milwaukee's Juan Nieves and Cleveland's Greg Swindell.

Morgan did pretty much the same thing to them May 20 in Seattle when he pitched an eight-hitter. The Orioles scored two runs that day, on Jim Dwyer's homer.

Morgan also held Baltimore without a homer, only the second time that has happened in its last 21 games. The Orioles still lead all of baseball with 77 and have one more day to add to their major league record of 57 in a month.

Morgan illustrated how control and changing speeds can overcome an average fastball. The majority of his 107 pitches were clocked between 84 and 90 mph.

The Orioles got only six singles and Fred Lynn's double. They also had two base runners simultaneously only three times; one got as far as third.

"I kept the defense on their toes," Morgan said. "I threw strikes. Plus, with 12 runs, I'd better win. I was keeping the breaking ball down and that makes a big difference. I'll tell you, 107 pitches felt like 190 it was so hot out there."

His counterpart, Bell, began the game having allowed only three homers in 45 2/3 innings and none in his last 30, a span of five starts. That streak ended in the fourth when Valle and Presley connected in succession for a 2-0 Seattle lead.

He worked out of a bases-loaded situation later that inning but rediscovered trouble in the fifth beginning with a two-out walk to Valle. Valle moved to third on a single by Presley and scored when Knight failed to catch a pickoff throw from catcher Terry Kennedy.

"I felt good," Bell said. "I made a bad pitch to Presley for the home run, but the others weren't bad at all. They ended up with six hits, but I was keeping the ball down and felt good. I'm not going to worry about a game like this."

It went to 7-0 when the Mariners scored four more in the sixth. John Christensen led off the inning with a single, and was bunted to second by Bob Kearney. Rey Quinones singled to right for one run, and Ripken Sr. brought in left-hander Jack O'Connor, who faced nine batters and got three of them out.

Harold Reynolds greeted O'Connor with a double. Quinones stopped at third, and John Moses was walked intentionally to load the bases. Phil Bradley scored Quinones on a sacrifice fly, and the Orioles should have been out of the inning when they trapped Moses between first and second after the catch.

But first baseman Eddie Murray's throw to second hit Moses in the back and skipped away. That became important because Valle lined a single to center for two more runs.

The Mariners made it 10-0 in the seventh, Reynolds singling in two runs and Moses one. Presley's two-run homer off Tom Niedenfuer in the ninth finished things.

Orioles Notes:

Baltimore is 18-9 on the road, 8-13 at home . . . Until last September, Morgan was 0-8 against the Orioles. Since, he's 3-0 with three complete games and a 1.00 ERA.