I think a few people need to snap out of this simplistic idea that we have a best XI which will always be our go-to lineup if everyone's fit. Different games call for different kinds of players, and as good as the Cork/Schneiderlin pairing has been, that doesn't mean it ticks every box. Both Wanyama and Nainggolan offer height and strength, which are things we've perhaps been lacking in the middle. Wanyama can also play at CB, where we all know we're lacking in quality, and Nainggolan can play in the AMC role or even out wide, so both players would bring new options to the team and a multitude of different ways we could set up. Perhaps signing one of these players would mean that Cork starts 15-20 games in a season, rather than all 38, or perhaps Cork, Schneiderlin and the new guy could all be played together while Ramirez plays out wide or drops to the bench.
Options, people. They're important.