I have to also point out that Newcastle looked absolutely tired after their Chelsea match at the weekend. No excuses really regarding fitness differences of both clubs. Both clubs are tired.
There has to be a reason he didn't play today. If it's not an injury/discomfort, I fear that he was either late for training again or Flick doesn't have confidence.
Great match and seems very composed. La Masia overall has been producing much better players in the last 4 years or so. Physicality is not there but can be great for LL and CDR as mentioned above