As a late discoverer of this site, I have not been able to comment on previous discussions about this topic, but I do think that there are some aspects of this which should be considered.
When discussing the best drafts in WNBA history, 1999 always comes up at the top of the list. However, if you look at it in detail, it is basically an ABL dispersal draft. 35 of the 50 women chosen in that draft were from the ABL. 2 other ex-ABL players, Katie Smith and Shannon Johnson, were allocated to Orlando and Minnesota which were new franshises that year. In fact, 46 former ABL players appeared in WNBA games that season. So, out of 132 roster positions, over 1/3 were now held by players from the rival league. In the following year, there were 61 playing in the 16 team WNBA!
As has been mentioned, there have been 84 ABL players who made WNBA squads at some time in the W's history. There were only some 164 women who ever played in the ABL in its lifetime, so over half made it into the newer league. So, if the opinion of the WNBA management is taken into consideration, they believed that there were better players in the other league, or they would not have offered jobs to so many. But, to make the ultimate argument, with a 9 team league, there were never more than 90 ABL players at a time --- yet 84 were given spots in the WNBA. So it was not just the starters, but practically every bench player as well, who were wanted in the WNBA!
Looking at the statistical side of the equation, the average ABL player in the WNBA has outperformed the non-ABL players in terms of games played, total assists, total rebounds, and total points, as well as rpg, apg, and ppg. These numbers do not include any of the ABL numbers, just their WNBA numbers, so the career totals are very illustrative since each player has lost one to three years of their careers playing in their other league.
By my count, there have been 770 women who have played in at least one WNBA game, so there are 686 who have only played in this league. Those 686 have the following averages for their careers:
89.09 Games, 289.74 Rebounds, 143.10 Assists, 651.62 Points, 3.25 RPG, 1.60 APG, and 7.30 PPG.
For the 84 ex-ABL players, it reads:
117.92 Games, 404.68 Rebounds, 209.89 Assists, 896.60 Points, 3.43 RPG, 1.78 APG, and 7.60 PPG.
Now, since we are down to Delisha Milton-Jones as the last representative of the ABL, these numbers are near to being complete and utter history. The career averages will then become moot, as there will always be rookies coming in and ending a veteran's career. But the per game average will remain as a basis for comparison.
Finally, both the All-Decade and Fifteenth Anniversary teams elected 3 ex-ABL players, with 4 others being nominated. So 7 of the 30 greatest players in the league's history are considered by all to be among the best.