The data they get will be delayed.
Not in Star Trek. With the technology of the show, the communications lag across ten lightyears is a millisecond!
I find it incredible they can find that many ships to fight an invader when usually there is only one ship in range to save Earth.
In "Best of Both Worlds", Earth got a warning about five-six days in advance, and managed to summon about 40 ships. Also, that was in peacetime.
In ST:FC, we don't know the length of the advance warning, but once again the Borg fly in from the outer fringes of the UFP - so an advance warning of about a week is quite possible here as well. Also, war with the Dominion is imminent. Earth could have prepared a defensive fleet. Or, perhaps more probably, Earth would be amassing an offensive
fleet, to be deployed at Bajor later on.
The latter idea would also allow us to assume that the ships being gathered were not particularly good at defense. Many (say, the odd-looking and nearly unarmed Steamrunners
) might have been dedicated to planetary assault and for that reason would contribute little to the battle but the pretty visuals of their destruction. Hence, the arrival of the E-E would make all the difference, in a way the arrival of the E-D would not have affected the earlier Wolf 359 battle in any way since there were already plenty of Nebula
caliber ships there.