Counting stats are for the, well, they certainly don't favor the birds in this case because:
Skylar: 150 games played
Sue Bird: 118 games played.
Playing just 8 games in your freshman year hurts your career totals.
Assists per game are even at 5.0 but Bird's A:TO ratio is 2.1 while Diggins's is 1.5.
Sue was also a much better shooter:
SB: 48.1%, 45.9% 3-pt
SD: 44.8%, 35.0% 3-pt
(Despite all the practice she got at the line, Diggins also was worse than Bird at free throw line: 89.2% vs. 77.9%)
And Diggins took about 3.6 more shots than Bird per game.
Also, Sue won the Lieberman award three times.