Top Japanese female wrestler Io Shirai, who was scheduled to sign with WWE, made a surprise return to Stardom at the July 30th event in Shinkiba.
According to The Wrestling Observer, Shirai announced she was leaving Stardom several months back to take time off to heal up the nagging neck injury. The feeling is the real reason why she bid her farewell to Stardom is because she was planning to sign with WWE, however she was not permitted to disclose that information.
The report adds that no one has directly said WWE decided not to offer Shirai a contract due to the neck issues they discovered during her medical testing, but the company stalling on offering her a deal made it very likely the neck issues were the reason for the delay. WWE then wanted Shirai to take time off to rehab her neck, which she did, and recently received clearance to return to the ring. However, for whatever reason, WWE decided against offering her a deal, and she returned to Japan.
While all injury cases are different, WWE has had a general rule of not signing new talent with previous neck or concussion issues.