Maryland at North Carolina last night, played at 7:30 but showing delayed to 11 p.m. on Channel 20. How could they?

The purveyors of college basketball for televison brought it on themselves with oversupply, but when a live one gets away, there's a hue and cry from an audience made insatiable. Forcing explanations.

Blame (?) Atlantic Coast Conference rules in this case.

Maryland-UNC could not be shown live, ACC Commissioner Bob James explains, because no other conference schools may be on the tube in conflict with an ACC network (C.D. Chesley) game. And there was a Chesley game last night, 9-11 time slot: Virginia-N.C. State. No way then, that Len Klompus and his Rockville-based MetroSports, which packages Maryland games not on the Chesley schedule, could get the Terps on until after 11. In fact, says James, the ACC made a special exception to allow the delayed showing, since it usually permits that only on home games.

But why wasn't UM-UNC the ACC game? Well, the conference requires that the ACC team that is on the network the most can be on no more than three times more than the team appearing the least; got that? So Clemson at Georgia Tech was supposed to be the Jan. 7 game; niether Channel 7, which has first right of refusal, nor 20 wanted that one in prime time. But wait. Georgia Tech decided to see how it would draw in Atlanta's Omni and requested the game not be telecast (although counting against the limit). Hence the switch to Cavs-Wolfpack.

So why didn't WJLA-TV-7 or WDCA-TV-20 go for the Virginia game? Well, it would have bucked Channel 5's Georgetown-St. John's, but don't ask us. Ask them. Next time, too, okay?

Larry holmes can't get enough TV exposure. The successor to Muhammad Ali (who was trying at last word to get the Hawaii Boxing Commission to let him fight Englishman John L. Gardner) wanted five fights in 1981 before bowing out but says the networks aren't offering enough to make projected bouts with Marty Monroe and Trevor Berbick worth is while. . . One more gun victim: Ronnie Harris, 22-3 as a pro welterweight after winning a bronze medal in 1964 Olympic boxing; accosted and slain New Year's Eve in Detroit. . . Kronk Boxing Club of Detroit, meantime, is due here to take on the Maryland-National Capital Park and Planning Commission team, 5 p.m. Saturday at Seat Pleasant Rec. Center; proceeds toward a bus for the center. Dave Jacobs, the fight trainer, says Motor City's WBA champs Thomas Hearns and Hilmer Kenty will be guests there and at a Sunday benefit reception/fashion show at Foxtrappe, 16th and R NW. . .

Steve Rosenbloom, New Orleans Saints general manager, has been interviewing coaching prospects but owner John Mecom Jr. keeps interviewing Bum Phillips. Bum sure don't want no Beathard-Pardee situation but Mecom says Steve stays. . . UPI's media panel names Atlanta's Leeman Bennett NFC coach of year, landslide. . . AP's selectors, after making Brian Sipe Nfl MVP, go for Earl Campbell as offensive player of year, 43-26 over Sipe.