Tier 1 is the two best players on the teams that have won the past 2 championships. Just as Maya Moore and Candace Parker traded championships in the middle of the 2010s, so Elena Delle Donne and Breanna Stewart have been the best players on teams that won the past 3 championships.
I value versatility in players on both offense and defense, maybe to a degree that is unwarranted. But part of the reason Stewart and Delle Donne are tier 1 is they can both function as the fulcrums of their offense, while also being dangerous off ball, against set playoff defenses, when scoring is toughest. Stewart could defer to Jewell Loyd if her matchup was more favorable, as could Stewart with Emma Meesseman or Kristi Toliver.
In the next couple of years, I imagine we will have more than just the 2 players I list here as solo tier 1 players. A’ja Wilson is already close to making it me have a tier 1a with these two and her at tier 1b. Another year and definitely another 2 years of similarly high level play will put Wilson there. Of course, maybe she simply joins tier 1 with no qualifiers, as she is certainly capable of doing.
The interesting thing about Breanna Stewart is that she is not truly exceptional at any one part of the game. You can point to someone in the league who is better at any isolated part of the game, whether it be passing, shooting, defending the rim, defending on the perimeter, scoring in the post against smaller players, or whatever discrete skill you want to point to.
What makes Stewart special is that she is very good at any discrete skill you want to point to as important in modern basketball. The flip side of their being nothing she is exceptional at is there are no holes in her game. She can be paired with almost any lineup configuration and fill in the holes in the lineup. There are far fewer fit concerns with the kinds of players that can be put next to her than with almost any other player.
Of course more shooting is good, and Seattle has done a great job spreading the floor, but she can work in tighter spaces, and has taken more 3s herself every year she is in the league. She can provide spacing next to a more dominant post player, something she does for her super team in Russia, where she plays with Jonquel Jones and Maria Vadeeva.
Maybe the most impressive thing is she has not even really entered her prime yet. Really, this next season, her age 27 year, is her entering her prime. Stewart is on pace for entering her name in the GOAT conversations, alongside the likes of Cynthia Cooper-Dyke, Tamika Catchings, and Dianna Taurasi. I am not that interested in finely deciding between various contenders, but I do like noting who has an resume to be included, and am excited to watch Breanna Stewart continue to play at a high level.
Elena Delle Donne
Unlike Stewart, Delle Donne has one exceptional talent, shooting, and has diligently worked to round out the rest of her game. Her prime has come a bit later in her career, but is no less impressive for all of that. Her Mystics team in 2019 had one of the most dominant offenses of all time and I can not wait to see how the team looks in 2021, given the turnover of the roster.
Elena Delle Donne is on pace to be the greatest shooter in WNBA history, and she has done that while also being 6’5”. The only WNBA player so far to shoot 50/40/90, she is able to warp defenses by herself, as she can bury an opponent in threes both in the half court and as a transition shooter if they lose track of her.
Elena Delle Donne is not the defender, especially on the perimeter, that Stewart, or even A’ja Wilson, is. But she is a good defender. This was most notable in the finals against the Connecticut Sun in 2019. Game 2, the one that EDD missed after injuring her back, was not coincidentally, Jonquel Jones’ best game.
Elene Delle Donne is not going to rack up highlight blocks, but she is adept at using her size to force tougher shots at the rim , is strong enough to hold up in the post against big centers, and is a good rebounder.  She moves her feet fairly well on the perimeter, teams do not try to target her in the pick and roll.
The main factor that could lead to Elena Delle Donne falling down this list his health. Her two best attributes, shooting and being tall, won’t diminish with age. But she is someone who has a now well documented struggle with complications of lyme disease, as well as a history of nagging injuries. Otherwise, she should be able to remain effective well into her 30s.
The next step in her evolution as an offensive player may be to truly take advantage of shooting deep 3s, similar to how Diana Taurasi has used the that shot to extend her career. That might be wishful thinking on my part, as watching EDD shoot 3s from 30 feet sounds awesome, and like something she should be capable of doing. Whatever she does, I do hope we get a playoff series at some point between Elena Delle Donne and Breanna Stewart when both are healthy.
 I am going to become a broken record on that, but the biggest lack right now in data for the WNBA is tracking data. This would tell us, among other things, the percentage of shots which various rim protectors allow at the rim. I suspect EDD might be harder to score at the rim against than Brittney Griner, though Griner blocks a lot more shots, but I have no way to prove it, as I could with NBA defenders.
 Initially I wrote that she improved her rebounding, because her rebounding jumped after her second year in the league. But in looking more at that Sky team, the real change seems to be going from playing with one of the best rebounders in WNBA history in Sylva Fowles in her first 2 years, to not playing with Fowles. Good reminder to make sure to look for alternate explanations, not just the obvious one.