It did the Texas Rangers' morale no good to see their whole infuriating season capsulized in one marathon 2-1 defeat to the Baltimore Orioles yesterday in 12 innings.

"I feel like I've seen this game over and over all season," said Texas Manager Billy Hunter, a placid man reduced a biting of his words. "Frustrating days, a whole season of them. What do ya tell 'em? Hang in there?

"It starts to sound hollow."

The Rangers, baseball's mystery team, have no idea what to make of themselves.

"We came out of spring training and thought we'd be on fire every day," said reserve shortstop Jim Mason. "I guess we thought people would look at our lineup and roll over. They ain't been rollin' over."

"The best team in baseball . . . that's what we thought we'd be for sure," said Kurt Bevacqua. "We won 94 last year and look at the players we added . . . Al Oliver, Bobby Bonds, Fergie Jenkins, Richie Zisk, Jon Matlack."

If any team in baseball looked loaded, it was Texas.

Now the Rangers look at each other and wonder. What's wrong with this 45-43 team that keeps spinning its wheels, dawdling in third place three games behind California.

This was the afternoon the Rangers thought they would cross the top of the hill and start the long glide toward their first West Division flag.

"We're scored 34 runs in our last four games," said Hunter. "Maybe this is it. But we've thought that a lot of times before.

This time an undistinguished pitcher - the O's Joe Kerrigan (5.86 ERA), making his first major league start after 119 relief appearances - held Texas to four hits and one run for seven innings. Relief ace Don Stanhouse followed with five shutout innings until Bird pinch hitter Terry Crowley could single off Reggie Cleveland to bring home Kiko Garcia from second with two out in the 12th.

The less famous the pithcer, the less prestigious the opponent, the worse the Rangers play. Against teams with winning records, Texas has played .620 ball. Against the losers, the Rangers are .385.

"Doesn't make much sense, does it" asked Hunter. "We do things kinda backwards."

The hallmarks of these Rangers are the wasted opportunity, the defensive error, the mental blunder. All were on display at Memorial Stadium yesterday.

The Rangers stranded men at the corners with one out in the first inning. It was just the beginning.

"That's where we lost," grumped Hunter. "Not getting Kerrigan out fast." Texas did not score in the fifth and ninth because, in large part. Bert Campaneris and Al Oliver could not lay down successful sacrifice bunts, baseball's simplest offensive play, at least in theory.

In the ninth, Bevacqua grounded into a bases-loaded, inning ending double play. In both the ninth and 10th, Stanhouse generously gave Texas a leadoff walk and each time the Rangers failed to punish him for his largess.

The Rangers, by contrast, pushed the O's winning run to second with a walk before Crowley's single to left.

"How come when we get those same opportunities we don't do anything?" asked Hunter.

However, Hunter knows why his team has launguished all season, going on small streaks that raise hopes, then losing an equal number of games with atrocious play.

"We've played some pretty shabby baseball," said the manager. "We've got 91 errors in 88 games, and that doesn't show the mental errors.

"We've been in an incredible team hitting slump all year and those fundamental errors eliminate you from winning the games when you don't hit.

The 2-1 loss in extra innings was a perfect example.

"Some guys have been taking their bats out to their positions with them," added Hunter. "I wish they'd leave 'em in the dugout."

Bavacqua was the main culprit yesterday, accounting for seven Texas outs (two double plays), in an 0-for-5 day, then compounding his misery by booting grounders in the eighth and 10th.

"You have to separate the bat from the glove," said Hunter. "You can't let a slump with one infect the other."

Baltimore and Texas offer magnificent contrasts. The talent-thin Orioles have been outscored by 61 runs, yet are eight games over .500. Texas has outscored its foes by 25 runs, yet is only two games over .500. Seem impossible?

"It don't surprise me," snorted O's Manager Earl Weaver, whose team has been outscored, 19-11, in the last three games with Texas, yet has won two of the three. "Who is going to say why."

The answer is that Texas is a poor close-game team, weak in the bullpen, careless afield and mentally sloppy. In other words, the opposite of Baltimore. In games decided by one and two runs, Baltimore is 16 games over .500, the Rangers one game under .500.

"During the All-Star break, Hunter wrote down the pertinent statistics of his players: Mike Hargrove, .303 career average; Campaneris, 608 steals; Toby Harrah, 27 homers last year, Bonds, 37 and Zisk 30; Bump Wills, .287 as a '77 rookie; catcher Jim Sunberg, hitting better than .325 since last July.

The Rangers' steady five-man pitching rotation of Jenkins (9-4), Matlack (7-8), Dock Ellis (8-4), Doyle Alexander (6-5) and Doc Medich (4-4) can't wait for those days to arrive.

"Our pitching has been better than anybody expected," said Oliver. "All our problems are us hitters' fault."

Exhibit one on the Ranger misery list is Matlack. The curveballing south-paw worked the first 10 innings yesterday, lowering his ERA to 2.31, second lowest in the league. Once again, lack of support kept him from victory. MatLack has not won a game on the road this season.

Matlack is not the only snake-bitten Ranger; the whole team plays with a black cloud over its head.

No sooner did outfielders Oliver and Juan Beniquez return to the lineup last Friday, after each had spent a month on the disabled list, than Harrah and Zisk went to the bench with sprained wrists.

"When Oliver and Beniquez hit homers in their first at-bats back in the lineup, I thought that might be our inspiration," said Hunter, looking down at his desk. "Then Toby and Richie come in the next day and could not play. That's the story of our whole season."