(FORTUNE Magazine) – Poor Larry Tisch. First his CBS management team got bad-mouthed by Dan Rather and others in the news division for closing bureaus, firing employees, and slicing $30 million from the $300-million news budget. Now the news-viewing public also seems to be turning on Chief Executive Tisch. Recent Nielsen ratings for the CBS Evening News With Dan Rather hit a 23-year low. After a two-decade reign as No. 1, CBS's nightly news program languished in third place for five straight weeks. On the sixth week it moved up to second, sending ABC's World News Tonight with Peter Jennings to the bottom of the heap. Through it all NBC's Nightly News With Tom Brokaw reigned as No. 1. NBC is rolling on in spite of a strike by the National Association of Broadcast Employees and Technicians, which represents 2,800 news writers, cameramen, and engineers. In January the network, a subsidiary of GE, set up special ''strike schools'' to teach executives how to put a show on the air. The company has actually saved money by operating with 700 quick studies instead of 2,800 professionals. This year the CBS TV network is expected to earn less than $50 million, vs. an estimated $90 million in 1986, though corporate profits, which also include records and publishing, should be above last year's. Ratings are drooping not only for the evening news but also for important prime-time shows. During the September-through-Apri l season, CBS scored its lowest ratings ever in the 8 P.M. to 11 P.M. slot, beating only beleaguered ABC. Both the laggard networks recently dropped contracts with A.C. Nielsen, whose new ''people meter'' rating device suggests TV programs draw smaller audiences than the networks had believed (FORTUNE, July 6). Edward Atorino, a broadcast analyst at the investment firm Smith Barney Harris Upham, recently pulled CBS off his firm's ''recommended'' list, citing a soft advertising market and ''lousy viewing numbers.''