With CBS sacrificing most of its week to baseball-playoff coverage, ABC has stolen the prime time Nielsens lead for the Oct. 5-11 period.Keys to the easy ABC win were the highest-rated “Monday Night Football” telecast since Dec. 3, 1990, ABC’s usual Tuesday and Friday strength and a rare Sunday victory courtesy of the vidpic “Overexposed.” While CBS was beset with minor year-to-year losses from its baseball coverage , NBC had to deal with a discouraging fourth-consecutive last-place finish among the nets. NBC’s pursuit of the adults 18-49 demographic has paid off to some extent, though, since the Peacock has beaten CBS two of three weeks this season in that race. Last week’s adults 18-49 standings were: ABC, an 8.5 rating, 22 share; NBC, 6 .6/17; CBS, 6.2/16; Fox Broadcasting Co., 5.6/15. ABC is now well ahead in that key category for the season and a competitive second in household ratings, the only network ahead of its year-ago average by that measure. Results from CBS’ baseball-playoffs coverage are mixed so far, down 3% overall from an 11.9/21 at this point a year ago to an 11.6/21 this year. The top rating so far this year is last Friday’s 12.7, while last year at this point the playoffs had already scored 14.0 and 14.5 ratings. The biggest difference appears to be softer interest this year in the Atlanta Braves, whose last-to-first rise in 1991 created a national fervor apparently not being equaled this year. Interest on the American League side may be slightly higher this year with the replacement of the smaller-market Minnesota Twins in ’91 with the popular, star-studded Oakland Athletics in ’92. In addition to its minor drop in playoff ratings so far this year, CBS must hope for a dramatic wrap-up from at least one of the ’92 series if it’s to have a chance of equaling the ’91 playoffs’ brilliant concluding ratings. Last year Atlanta won two games in Pittsburgh to triumph in that exciting seven-game series and produce the two highest-rated playoff telecasts of the last three years. Baseball finally took a break on Monday of the current week, allowing CBS to win a night for the first time in more than a week. Top-rated CBS entries that night were “Murphy Brown” (19.2/28) and “Northern Exposure” (16.8/27). NBC was a strong second, aided somewhat by the conclusion of “Lady Boss” (14. 2/22), which earned a two-night average 13.4/21. That puts “Boss” ahead of the ratings of six of the 15 firstrun multi-parters aired in the 1991-92 broadcast year. At 8 p.m., the Peacock’s “Fresh Prince of Bel Air” (15.3/24) moved back into the time slot lead after a six-week stretch, as CBS’ 8-9 p.m. sitcoms slipped to season lows. ABC continues to score well with “Monday Night Football” (16.2/27 for a one-sided Washington-Denver game), but the survival chances are looking slim for “Young Indiana Jones Chronicles” (6.2/10). ABC has 25 episodes of the show for this season, however, and will likely give it a shot on another night. ABC put an exclamation point on its lopsided Oct. 5-11 weeklong win with the strong performance of its vidpic “Overexposed” Sunday night. The Marcy Walker-Dan Lauria telefilm grabbed what was just ABC’s second Sunday win since last April 12. CBS sacrificed the night with baseball coverage, which sunk the net to third even though baseball faced nothing but presidential-debate coverage for the first 96 minutes of prime time. Saturday remained in the NBC column, though baseball knocked in CBS’ strongest Saturday share since last May 16 (when CBS reran “The Color Purple”). All three nets continued their anemic 8-9 p.m. performances, as Fox’s “Cops” continues to lay down the law that hour, both in households and in demographics. Friday saw ABC edge out CBS’ baseball, despite low numbers from a Perot half-hour campaign ad on ABC. “Camp Wilder” looked a bit sunnier in the 9 p.m. slot, where it equaled ABC’s best share there since last April 3. NBC’s struggling Friday lineup rebounded slightly against baseball and Perot, but is still way back in third. Thursday’s household race went down to the wire before NBC’s lineup edged out baseball, but the adults 18-49 race went much more easily to NBC. Still, the Peacock ran fourth in the 8-9 p.m. hour in households (second in adults 18-49). Fox got a minor ratings jump at 9 p.m. with a special “The Edge,” but “Flying Blind” crashed to usual “The Heights” depths at 9:30. The pair of specs did win the hour for Fox among teens. ABC’s “Room for Two” upgraded nicely after registering rundown numbers at the start of the season. Last week “Room” ran an encouraging 6% ahead of its “Delta” lead-in against unusual competition. The top rating that half-hour came from Fox’s “Martin,” a first for that rookie sitcom. Baseball nabbed CBS’ best Thursday share since Aug. 13. Wednesday went solidly to NBC once again, as ABC’s “Home Improvement” is starting to look like a mere tacked-on addition of Nielsen strength to an otherwise shaky schedule. For example, at 9:30, “Laurie Hill” plunged 33% below its “Improvement” lead-in. Also, viewers turned away from “Civil Wars” again after the previous week’s nude scene had attracted an eye-opening second-place rating. Last week’s fully clothed “Civil” episode dropped in rating by 17% compared to the previous week, while the competing “Law & Order” enjoyed a rousing 36% improvement and its best share since Jan. 7. On Tuesday, the opening game of the baseball playoffs proved to be a fat pitch for ABC’s lineup, which equaled ABC’s second-best Tuesday household share since the February sweeps. CBS did surprisingly well with its half-hour Ross Perot ad–an estimated 20 million viewers tuned in for at least some portion of the political pitch. “Dateline NBC” also reported its best numbers since April 14. Monday’s competition was sacked by ABC’s Philadelphia-Dallas “Monday Night Football” game, the highest rated “MNF” gridcast since Dec. 3, 1990 (Daily Variety, Oct. 7).