Science fiction digests are a balancing act. An editor has to fill a set number of pages every month relying solely on the stories s/he's got at her/his disposal. Not to mention the restrictions imposed if one wants to publish an "all-star" or otherwise themed issue.
Analog has got the problem worst of all of the Big Three mags. Galaxy is a larger digest, so it has more room to play with. F&SF tends to publish shorter stories, which are more modular. But Analog usually includes a serialized novel and several standard columns leaving only 100 pages or so in which to fit a few bigger stories. If the motto of The New York Times is "All the news that's fit to print," then Analog's could well be, "All the stories that fit, we print."
How else to explain the unevenness of the October 1961 Analog?
(see the rest at Galactic Journey!)