#4. Jinder Mahal - Out of WWE TV from June 2019 to April 2020

Jinder Mahal had an underwhelming 2018 despite having won the WWE Championship in 2017. In 2019, he moved back to SmackDown, but his luck in WWE wasn't the same.
He was in a different position, and not long after, he would be out of WWE for 10 months after suffering a knee injury. Despite the 6-12 month post-surgery recovery time, many expected Mahal to return to WWE TV between 6-8 months. Unfortunately for him, his return was cut short due to complications in the knee - having to go through surgery again.
#3. Aleister Black - October 2020 to present

Aleister Black's WWE main roster run has been unfortunately underwhelming. While he was utilized heavily on WWE programming during Paul Heyman's reign as RAW Executive Director, the latter's departure has affected the Dutch Superstar directly.
He hasn't been seen on WWE TV since he was drafted to SmackDown in October 2019. After WWE released his wife Thea Trinidad (Zelina Vega), it seems even unlikelier for him to have a bright career with the promotion.