Hoch's annual sifting of all published U.S. mystery/crime stories (this year there were 426 to choose from) continues to produce ragged results: over half the selections are from Ellery Queen's Mystery Magazine (which has its own anthologies), and not one of the 16 stories for 1979 is really distinguished. Jack Ritchie is as charming as ever, and Ruth Rendell outclasses everyone in sight--but neither is at top form here. Barbara Owens' see-through ""The Cloud Beneath the Eaves"" is the winner of the Mystery Writers of America's Edgar award--further evidence of the MWA's taste for psycho-crime confessions. And no less predictable are contributions from Bill Pronzini, Jerry Jacobson (murder in a boys' prep school), and editor Hoch. Brian Garfield provides a sliver of espionage; there's serviceable private-detection from Ernest Savage and Francis M. Nevins, Jr. (with a nice Western-movie-buff background); and Frank Sisk's ""The Leech"" is a genuine stomach-turner--one of a few stories here that belong more rightly in a horror collection than in one called ""Best Detective Stories."" Slim pickings, then--plus the usual and welcome bibliographic appendices; perhaps in a more generous sampling (like the hefty Queen anthologies), the spotty quality might not be so noticeable or annoying.