1. 31,758 more people voted in the 3rd CD than in the 2nd CD. The reason for that would seem to be that people in the 3rd CD, whether Democrat or Republican, viewed the race as being close, whereas Israel was seen as a lock in the 2nd. And again, more than half of that difference came from the Suffolk portion of the 3rd.
2. Steve Israel won the Nassau portion of the 2nd CD that was formerly part of the 3rd by a margin of 78% to 22%. As I know many people who live in that part of the district who normally vote straight D down the line, it can be assumed that Dave would have won that area by the same margin.
3. Clearly this is speculation, but if you take the 36,506 people who voted in the Suffolk portion of the 3rd CD and assign that number to the Nassau portion of the 2nd CD, and project the vote at the 78-22 that it came out for Israel/Bugler to Mejias/King, and add the totals to the 3rd CD race minus the Suffolk portion, Dave wins 89,703 to 84,519. Maybe this would not have happened, but the bottom line is that it shows that if the 3rd CD was reconfigured to its pre-2002 lines, it is at least a competitive district for a Democrat, whereas now it is not unless that Democrat was already known and popular throughout the district (remember, when the race started, 60% of the people in the district had never heard of Dave).
4. By the way, when doing this switch and adding back the Suffolk portion for the 2nd, Israel still wins 63%-37%. Not quite 70%-30%, but still very convincing, and evidence that he does not need the Nassau portion.