Rick Leach, third in the Heisman Trophy balloting after leading Michigan to its fourth bowl game in his four years at quarterback, signed yesterday with the Detroit Tigers - who drafted him first - and not the Denver Broncos - who drafted him on the fifth round.

"I'm going into baseball," said Leach, an outfielder who batted .349 in a 149-game collegiate career. "I'm through with football," declared the man who accounted for more touchdowns, rushing and passing combined, than any other player in NCAA Division I annals.

Leach reportedly impressed Coach Red Miller at a Bronco rookie camp last month, and was pursued by the Canadian Football League's Montreal Alouettes to the reported tune of $500,000. But he settled for an estimated $200,000 from the tigers, spread out over the next "few" seasons until he makes the majors, and said, "I'm not going to look behind me anymore."

So Leach follows last year's Tiger No. 1 pick, Michigan State All-American football flanker Kirk Gibson, into the organization. Gibson? Currently, it says here, "struggling to stay afloat at Triple-A Evansville" . . .

Orioles luminaries told a full house at the Touchdown Club yesterday how much the team needs Washington support.

And Hugh Steinberger, this year's TD prez, offered his good offices as a college roommate of Baltimore owner Jerry Hoffberger, "if they need any help to work things out" in any Balt-Wash developments. Steinberger and Hoffberger played pickup lacrosse together at U. of Virginia.

Rear Adm. William Porter Lawrence Jr., superintendent of the U.S. Naval Academy where he lettered in basketball before going on to bigger and better (and worse, six years a POW in Viet Nam), has been named winner of a most prestigious award: National Football Foundation and Hall of Fame Gold Metal . . .

Marvin Barnes, again: received his bachelor's degree from Providence College Wednesday! may get a shot with the San Diego Clippers; Coach Gene Shue feels he's worth the risk!! has engaged his lawyer and agent . . . William Kunstler!!!

When the cardinals of the Roman Catholic Church assembled in Poland for the pilgrimage of Pope John Paul II, who should show up as part of the faithful in Kracow? Mr. Cardinal, Stan (The Man) Musial, the old Polish Falcon of St. Louis . . .

In Houston, a jury has heard testimony from Janice Graham Johnson, 32 in a $500,000 lawsuit that glare from the Astrodome skylight caused her to be hit in the face by a baseball, breaking her nose, cracking her teeth. She is suing not only the Astro people, but the Phillies, who were taking batting practice when she was struck by hitter unknown as she sat in the center field bleachers one afternoon in 1974.

Testified Phillie Manager Danny Ozark: "Certainly we would never hit a ball in the stands intentionally."

The one and only Danny Ozark! CAPTION: Picture, Rick Leach