Going off on a minor tangent, is it possible that the Borg detected something strange about Sisko's lifesigns (since he was born from one of the Prophets that had taken human form) and blasted Saratoga to keep it from firing on the cube while they held it in a tractor beam until they could focus their attentions on beaming Sisko over to the cube for further study, or sending a Borg away team to seize him? After all, the possibility of finding something about him that would add to their perfection would help an in-universe explanation on why the cube tractored Saratoga instead of outright obliterating her, AND kept her tractored until her warp core went up...
Thanks to everyone, especially Timo and Crazy Eddie, for the vigorous discussions about the Wolf 359 battle. There are still some unanswered questions and I appreciate viewing the informed speculation. I'm still of the general opinion that Endeavour was present a la comments in Amasov's log as spoken of in Voyager's "Scorpion", took some damage that affected her communications (leaving her unable to send word to Starfleet or Enterprise-D that she had conducted rescue operations) and her ability to do battle, the crew warped a sufficient distance away from the battle scene to keep the ship from being destroyed, and after detecting that the Borg cube had moved along, returned to the scene of the battle to collect escape pods, beam out survivors from wrecked ships, etc, then warped away to the nearest Starbase (clearly, not Earth). Thus, when Enterprise-D arrived and scanned the wreckage and found no survivors, they were free to pursue the cube, both moving the plot along quickly enough but also providing an in-universe explanation for not needing to stop and conduct rescue operations, or detach a bunch of shuttles to round up escape pods and beam people out of wrecked ships while Enterprise-D continued for Earth.
And if I remember on-screen dialogue well enough, they DID scan the wreckage and found no survivors. There was no mention of scanning for escape pods specifically, but I can't imagine that the crew would NOT also scan for escape pods, which may or may not have moved some distance away from the battle, but would certainly be within sensor range. And if there were escape pods, or survivors on wrecked ships that had access to subspace communications, they would have sought help immediately once they saw a Galaxy-class starship prowling through the ship graveyard. And escape pods would have been actively looking for help once the Borg left, having no further reason to "lay low".
Now, I grant that escape pods might have turned off their transponders and distress beacons once they saw the cube tractor a bunch of them in for assimilation, that's entirely possible, but once the cube had left, they'd have turned them back on and waited for rescue. Even then, I find it difficult to believe that Federation escape pods could hide from Borg sensors. I would imagine the Borg sucked in enough personnel to make whole any losses they suffered during battle, then continued on their merry way towards Earth. That would both explain how Federation (and Klingon, from the handful of Klingon ships that Hansen said were enroute...) personnel were Borgified and found in the Delta Quadrant, as well as why Sisko and others survived...once the Borg had replenished any personnel losses, it would be irrelevant to continue to harvest the occupants of the escape pods, especially when they clearly had places to be and things to do. And this left Endeavour, no longer a threat to the Borg and well outside the area of battle, free to come back in and sweep things up when the cube left, conveniently leaving Enterprise-D free to come through the graveyard, pronounce everybody still around well and dead, and move along to Earth.