#2 SmackDown could use another top-level NXT star
Similar to the #4 slide, adding the talents of the former NXT Women's Champion to SmackDown would instantly reinvigorate the women's division. Carmella returned to SmackDown as a different character in November of 2020 following the WWE Draft.
After the 2020 WWE Draft, the SmackDown women's roster consisted of top stars Belair, Banks and Bayley. Banks had just won the SmackDown Women's title from Bayley at Hell in a Cell. Carmella would then challenge Banks in several title matches going forward. She was unsuccessful in each attempt.
Natalya and Tamina are veterans of the division but their best days are in the past. They are currently being pushed as threats to the WWE Women's Tag Team titles. The Riott Squad have primarily been used as a team and have traded wins and losses. They are also in the Tag Team Turmoil match at WrestleMania 37 but have not been built up yet as viable threats to anyone.
Billie Kay was also drafted to Friday nigths but has been used as a comedic character. That's all well and good because she knocks her segments out of the park every time she is on screen. Chelsea Green was supposed to join the ranks of the blue brand around Survivor Series but was hurt in her debut match.
There are a lot of names in the division but there is a clear divide. Banks, Bayley and Belair are the top three women at the moment. After losing most of her recent matches, Carmella has lost some luster. The rest of the roster has its roles, but those roles don't necessarily translate into serious title threats.
Adding Shirai to the SmackDown roster would help both NXT and the blue brand. NXT gets to run different feuds for the NXT Women's Championship with Gonzalez as Champion. Other women will debut and integrate themselves into the roster.
SmackDown would be getting one of the best wrestlers in the world. Shirai was regarded to be that before she signed with WWE. All of her work since signing with WWE and NXT has only confirmed that thinking. Big debuts always come after WrestleMania and Shirai joining SmackDown (if she chooses to) would certainly fit that bill.