Mike Flanagan, baffling Seattle on a controlled assortment of slow curves, changups and low fast balls, made short work of the Mariners with a left-handed four-hitter, guiding the Baltimore Orioles to yet another victory tonight at Memorial Stadium, 4-2.

Flanagan struck out six and walked one in going the route for his fifth straight victory and sixth against two losses lie retired 10 straight Mariners on the late stages before an error allowed Seattle a runner with one out on the ninth. An unearned run ensued.

Ken Singleto and, for a change, Mark Belanger gave Flanagan offensive support, keying a three-run fifth inning that nullified an until then strong effort by Mariner starter Rick Honeycutt.

Baltimore won its 19th in 22 games and retained a one-game lead over Boston in the American League East Seattle, yet to win at Memorial Stadium, lost its eight straight to the Birds.

The first Oriole run, scored in the third, was slightly tainted, at least in Mariner eyes. A one-out walk issued by Honeycutt to Al Bumbry followed by Belanger's single put men on first and second. Then second-base umpire John Shulock called Honeycutt for a balk with an 0-1 count on Singleton.

That brought Mariner Manager Darell Johnson out of the bullpen for an unsuccessful attempt at negotiation. Singleton hit the next pitch to centre for a sacrifice fly to score Bumbry. It was the big fielder's 25 RBI of the season, only his sixth hitting right-handed.

The balk call hurt Honeycutt because it took away the double play," Flanagan said. * "It seemed to rattle him a little bit. He wasn't doing anything overt, he just leaned a little or did something else different. I've had umpires call it on me for the same reason."

In the fifth, Singleton raised those figures to eight and 27 when he hit Honeycutt's first pitch into the rightfield stands to score himself and Belanger, who had just driven in Kiki Garcia with his first triple since 1977. The round-tripper was Singleton's ninth this year.

That made it 4-1, the visitors having made the boarin the inning of Mario Mendoza's run-scoring single.

Flanagan threw only 97 pitches in going the distance and was noticeably stronger in the final four innings, striking out three and allowing only two runners.

"Last year, I was throwing a lot of high, breaking balls and by the end of the game, I'd be dead." Flanagan said. "This year I'm getting the hard first balls low and inside and then taking something off them to the outside. It's a lot easier physically and will just make me that much stronger in the late innings."

During the last 22 games. Oriole hurlers have combined for a fine 2.15 earned run average. The staff has yielded an average of fewer than seven hits per outing.

Belanger, a .231 lifetime hitter, was struggling along at .116 for 1979 before going two for four tonight.

"I've probably heard and done everything possible to pull out of the slump," Belanger said. The short stop hit a low fast ball for his three bagger.

Except for three early walks, Honeycutt was strong until the fifth inning. The southpaw struck out five Orioles and gave up only one hit in the first 4 1/2 innings.