On May 25, about an hour before the Baltimore Orioles were to face the New York Yankees for the first time this season, Manager Lee Mazzilli told then-pitching coach Mark Wiley he wanted to run the standard pre-series pitchers' meeting himself. Putting aside advance scouting reports, Mazzilli, a Yankees coach from 2000 to 2003, stood before the Orioles' pitchers, described the tendencies of each Yankees hitter and dictated how each should be pitched to.

The Orioles were 20-20 at the time, still in third place, still within five games of the division lead. But the Yankees swept an ugly three-game series and battered the Orioles for 41 runs.

In many ways, the Orioles have not recovered; they were swept again by the Yankees in New York a week later, finished with the worst record in the majors in June (8-19), and when the first half ended Sunday, were 37-48 and in last place, 171/2 games back -- their worst first-half finish in five years. It was a sobering development for a team that fancied itself on the verge of contention.

The second half of the Orioles' season, which begins Thursday night with the first of four games at Tampa Bay, is charged with tension as speculation, inside and outside the organization, has begun that Mazzilli, in his first year as a big league manager, may be in danger of losing his job at season's end, if not sooner.

Owner Peter Angelos, after casting himself in recent years as a hands-off owner who no longer meddles in baseball operations, has stepped back in recently, according to several team sources. After spending over $120 million on free agents in the offseason, he has publicly challenged Mazzilli and is growing increasingly frustrated with pitching ace Sidney Ponson.

While Mazzilli is only halfway into his first season, already one critical component of a manager's security -- his hold over his players' faith -- is in question, as two veteran Orioles, neither of whom would agree to be identified, said last week that Mazzilli has lost the clubhouse.

"A couple of things frustrate guys in the clubhouse. I will say that," said Ponson, who declined to elaborate.

Many of the reasons for the team's first-half slide were obvious: a young starting rotation that has struggled amid injuries and inconsistency; a rash of injuries to key players such as Melvin Mora and Jay Gibbons; an offense that, while powerful enough to rank fifth in the league in hitting (.280), is batting .255 (next to last in the league) with runners in scoring position.

"I don't know too many teams that have lost guys in the middle of their lineup and their rotation all at once," Mazzilli said. "If we had our whole team out there in the first half, I think we'd be right on target."

However, upon closer examination, the first half of the season has shown the Orioles to have other issues -- from an owner who still dictates critical personnel moves, to a two-person front office that has alienated several key players with questionable personnel moves, to a new manager who was not allowed to choose his coaches and rarely consults the ones he was given.

Dysfunction pervades the lineup in that Mazzilli is forced to play two second basemen at once -- Jerry Hairston and Brian Roberts -- a seemingly harmless quirk that nonetheless has major consequences. Among them: several costly mistakes on defense with Hairston playing unfamiliar positions in the outfield, and a dangerous workload for catcher Javy Lopez, who on many days was blocked from an easier stint as designated hitter by the fact Mazzilli needed to use Hairston there.

Last week, before the team signed a third catcher to lighten the load, Lopez acknowledged to The Post he was fearful his knees "are gonna explode" from the workload.

Angelos has publicly challenged Mazzilli and his staff to turn the team around. Angelos has said the pieces are in place -- including Lopez, all-star shortstop Miguel Tejada and veteran first baseman Rafael Palmeiro, all of whom were signed as free agents this winter -- for the team to contend.

Meantime, Angelos is again hands-on. According to team sources who spoke on the condition of anonymity, he showed up minutes before the Orioles made their first-round pick in the June 7 amateur draft, and vetoed the front office's selection not once, but twice -- first nixing Florida State shortstop Stephen Drew, then Redan (Ga.) High School shortstop Chris Nelson, and mandating that the team select a college pitcher, which it did by taking Rice's Brad Townsend.

Angelos has focused much of his frustration over the team's poor performance on Ponson, the 27-year-old right-hander whom the Orioles lured back to Baltimore this winter with a three-year, $22.5-million contract after trading him to San Francisco last July.

After opening the season by winning his first two decisions, Ponson closed out the first half with nine straight losses to finish at 3-12, with an ERA (6.29) that ranks next to last in the league.

On June 4, according to team sources, Angelos was so upset about Ponson's performance and ongoing weight issues that he sent Russell Smouse, the Orioles' general legal counsel, to meet with members of the training and strength-and-conditioning staff.

According to those sources, Angelos was investigating the feasibility of trying to void Ponson's contract based on the "loyalty" clause in the Major League Uniform Player's Contract that requires a player to "keep himself in first-class physical condition," among other things.

Angelos, who declined to comment publicly on Ponson, apparently has dropped his pursuit of such action.

After failing to upgrade the starting rotation beyond re-signing Ponson, the Orioles' front-office tandem of Jim Beattie and Mike Flanagan backed him up with four young starters, none of whom had pitched a full season in the majors. It was a gamble the Orioles lost, as two starters (Kurt Ainsworth and Eric DuBose) have had arm surgery, and a third (Matt Riley) was demoted to the minors.

"Obviously, it was a gamble," said right fielder Gibbons. "Those were four guys with a lot of talent, but you're asking all of them to do the job, and it's hard for young guys to all four go out there and throw well at the same time."

Despite the emergence of right-hander Daniel Cabrera -- a contender for rookie of the year with a 6-3 record and 2.90 ERA since being called up in mid-May -- the rotation has the third-worst ERA (5.51) in the majors.

"You can see the pitching did not start too good, but it started doing better," Tejada said. "I think in the second half, everybody's going to have a big heart to have a better team. We had bad luck [in the first half]. But we are going to be pushing and pushing to get better."

The team's pitching -- particularly its league-leading walks total of 387 -- has frustrated Mazzilli above all. After remaining upbeat for much of the first half despite mounting losses, in recent weeks Mazzilli has taken on the look of someone resigned to an awful fate.

A dark-horse candidate when the team began searching for Mike Hargrove's successor, Mazzilli won the job largely on the basis of a dazzling interview, according to team officials at the time.

But in a highly unusual move, Mazzilli, who is signed through 2005, was not allowed to hire his own coaches, and was given Hargrove's entire staff -- two of whom, Rick Dempsey and Sam Perlozzo -- were interviewed for the manager's job. When the team fired Wiley on June 26, partly at Mazzilli's urging, Mazzilli again was not allowed to make his own hire. Instead, the team rehired Ray Miller, a close ally of Angelos and Mike Flanagan.

According to clubhouse sources, Mazzilli's relationship with his coaches is distant at best, cool at worst. "He doesn't engage them in any strategy discussions," one source said. "He does what he wants to do."

On Opening Night, as the Orioles were trying to hold off the Boston Red Sox in front of a national television audience, Mazzilli went to the mound in the sixth inning to make a pitching change, bringing in Rodrigo Lopez to face Johnny Damon. It was an unconventional move for that stage -- Lopez is a right-handed pitcher; Damon is a left-handed hitter -- but when it worked and the Orioles won, media reports hailed Mazzilli's willingness to go against "the book" of high-percentage matchups.

There was only one problem: According to clubhouse sources, when Mazzilli went to the mound, he told coaches he was bringing in lefty Buddy Groom. Somehow, signals were crossed, and Lopez entered the game. Because the result was successful, the mistake never came to light.

Other mistakes have been more obvious, such as the June 17 game in Los Angeles when Mazzilli went on the field to make a double-switch despite the fact the Orioles had no reliever ready in the bullpen. As the Orioles tried to stall, Lopez warmed up hurriedly, until the umpire rushed to the bullpen to demand the Orioles bring in a pitcher. Lopez could not hold a 3-1 lead, as the Orioles lost 4-3.

"There's been some high school stuff that's gone on around here," one Orioles veteran said. Of Mazzilli, the player said, "He's gotten a free ride [from the media], and it's been noticed in [the clubhouse]."

Lee Mazzilli, above, has been publicly challenged by Orioles owner Peter Angelos, who has retaken an active role in running team.