The Borg should have been 100 times the threat they posed during the entire series.
From "thousands of planets" they assimilated, at least ten would've been evolved beyond our imagination, giving the Borg knowledge and technologies beyond our ability to divert.
1 standard Cube (not even a tactical) took the near entire fleet down at Wolf 359, granted it was Jean-Luc Picard/Locutus on the Bridge with tactical insights, but even then: more than 10K lives gone, 39 STARSHIPS... eradicated in mere minutes...
Imagine what a fleet of standard cubes could do.
Someone, long time ago, made a digital replication of the cube's assault, spinning around at high velocity, becoming an all-sides-covering laser beam.
Considering the wreckage Enterprise NCC-1701-D
flew through, this could be amazingly accurate.
Especially, since a few ships seemed to be cut in parts, rather than exploded.
Then again, the Borg have a 'surgical cutting beam', used especially for taking ships apart, they could have used this beam as assault weapon on Picard's command.