I came to this conclusion both by watching my videotape of the ep, and by viewing several pics the Wolf 359 research has brought out, most notably a pic of the Nebula model Marcus Nee originally sent to Bernd, but that I have also.

Here is where the Nebula class Melbourne appears: As the Saratoga's escape pod jettisons, you can see both the Borg ship and the Saratoga. Up in the right hand corner of the screen, however, is a mysterious, stand-alone saucer wreckage. A lot of people had differing ideas as to just what ship that saucer represented. Some thought it was the U.S.S. Gage, others (like Frank Gerratana) thought it was the Excelsior class Melbourne because of a statement made in a DS9 making-of book. Well, Frank was right, but not about the model itself-it's the Nebula class study that was originally battle damaged by Okuda & Sternbach.

Get a good look at the wreckage. The Nebula is actually upside-down in the shot. My screencaps were kinda small and poor quality, but with continually viewing the scene on a big TV, plus with Markus' pic, I confirmed that the saucer's battle damage matches between the two. There are also two proturbances that you can see jutting out at the left end of the saucer. Again, using the upside-down perspective, the pylon attached to the rear end of the Nebula saucer (with the tiny 1/2500 nacelles) is visible as the lower, larger proturbance. The other, smaller proturbance is part of one of the larger nacelle's pylons.

The saucer is turned at more of an angle than its original appearance in BoBW, but it is the same model. So the DS9 book Frank refers to was correct by saying the wreckage was the Melbourne...just not the one everyone thought it was.