Angels Sink Lower in West : Baseball: They lose for the eighth time in nine games as Athletics win, 5-4.

Although Manager Doug Rader’s fate remains unclear, it’s clear the Angels have not found a way to end the slump that’s dragging them further out of contention in the American League West.

Jose Canseco’s 31st home run of the season, an impressive blast into the right-field seats off Angel right-hander Kirk McCaskill, touched off a burst of three runs in the fourth and two more in the fifth that carried the Oakland Athletics to a 5-4 victory Friday night at Anaheim Stadium before a crowd of 41,169.

It was the Angels’ eighth loss in nine games and 22nd in 31, and it dropped the Angels 12 games out of first place and 3 1/2 games out of sixth.

McCaskill (8-15) was unable to protect a 1-0 lead provided him in the first inning, when Luis Polonia hit an inside-the-park home run to left.

All five runs off the Angel starter were earned, leading to his 10th loss in his last 12 decisions. He walked three and gave up six hits over 4 2/3 innings.

The other grim numbers: the Angels have lost seven of the eight games they have played against Oakland this season and six of the seven games they have played on this nine-game home stand.

Dave Stewart (9-6) won for only the second time in his last five starts. Stewart has won 20 games in each of the last four seasons but has struggled this season, and he began Friday’s game with a 5.28 earned-run average. After a shaky first inning, he settled down until the sixth, when he yielded singles to Donnie Hill and Wally Joyner and a home run to Dave Parker, his former A’s teammate.

Stewart lasted 6 1/3 innings, improving his career record against the Angels to 13-5. Rick Honeycutt pitched 1 2/3 innings to set up Dennis Eckersley for Eckersley’s 31st save in 36 chances.

Oakland stretched its winning streak to four and remained four games behind the division-leading Minnesota Twins.

Polonia’s home run came on a 3-and-2 pitch off the end of his bat and to the opposite field. He took advantage when the ball took an odd carom off the wall. As left fielder Rickey Henderson stumbled, the ball rolled toward the left-field bullpen, and Polonia made it home easily, recording the 19th inside-the-park homer in club history and the second of his career. Each has been off a team Polonia played for: He began his career with the Yankees, and he hit his first inside-the-park homer against them, on Aug. 14, 1990.

The homer was also Polonia’s first against an AL West team. He has hit 13 homers in four-plus seasons.

The Angels kept the inning going when Hill reached on an infield hit and took second when second baseman Mike Gallego’s throw sailed well past first, but they couldn’t capitalize on that opportunity. Joyner flied to center and although Dave Winfield walked, Parker grounded into a double play.

McCaskill cruised through the first three innings but the A’s solved him in the fourth. Canseco led off with his 31st homer of the season and 10th since the All-Star break, a long drive into the right-field seats that he paused to admire after it left his bat.

Harold Baines followed with a double to left, and he scored on Terry Steinbach’s double to right. Steinbach tagged and took third on Mark McGwire’s fly to right and scored on Gallego’s fly to right.

In the fifth, Oakland did its damage after two were out. McCaskill walked Canseco and Baines, who both scored when Steinbach lined a double over third base and down the left-field line.

Pitching coach Marcel Lachemann, who had visited the mound once before, went out again. This time, it was to take McCaskill out of the game.

That put reliever Chris Beasley in the game for McCaskill, and Beasley ended the inning by getting McGwire to pop to first.

Rader accompanied McCaskill into the clubhouse after the right-hander was taken out of the game and the Angel manager remained inside for much of the inning. However, he had returned by the time Hill and Joyner hit back-to-back singles in the bottom of the sixth.

It was worth Rader’s while to come back.

Although Polonia was thrown out stealing second for the second consecutive at-bat--he had been nabbed by Steinbach after he singled in the third inning--Hill singled to left and Joyner singled to center to keep the inning alive. Parker then slammed a 1-and-1 pitch over the fence in left-center to trim Oakland’s lead to 5-4, his 11th homer of the season and fourth of his career off Stewart.

The crowd roared, and in the owner’s box high above the field executive vice president Jackie Autry pumped her arm in delight.