Ruiz would be a decent squad player, I'm not saying he wouldn't be. But Rodri is 28, Kovacic 30, KDB 33, Bernardo 29. In my opinion the squad structure needs a 6/8 thats either younger and more of a long term option (e.g Neves/Wharton), or someone significantly better than Kovacic (e.g Kimmich/Bruno G), which I dont think Ruiz is. A 28 year old that cant nail down a starting spot in a midfield far worse than ours fits neither of these options even if he had a good Euros. Could possibly see him being an option if Kovacic would leave or as a last resort panic buy in the final days of the transfer window if we are unable to sign someone that would better fit the squads needs.
Just my opinion :)