This is horrible timing for him if he is out long
Per PWInsider...
Kurt Angle announced that Samoa Joe had won the fan voting to team with Bayley in the Mixed Match Challenge but "due to an injury" on Raw, Joe would be unavailable, therefore Elias will be teaming with Bayley.
While we are uncertain of the nature of the injury at this time, WWE sources have confirmed this is not a work and Joe is legitimately injured. We are working on confirming additional details, but this is horrible timing as Joe's work has been absolutely fantastic of late.