Yup, the guy is obviously still adjusting to the new enviroment.
And tbf, overall he had a decent game today compared to the last one when he seemed totally lost, clearly still needs time to gel with his teammates but some signs of improvement are already there, almost certainly will get better and more reliable with regular playing time.
we have a stacked midfield, and old guys like matuidi and khedira are doing pretty well. it's a long season, rabiot will get his chance once fatigue and/or injuries and/or dip in form kicks in.