Kimmich is a young defensive midfielder - born February 95 - who comes out of the youth of VfB Stuttgart. He was sold to RB Leipzig with 18 with a buyback clause and played as a regular starter there in the first year in the 3rd and in the 2nd year in the 2nd Bundesliga. It is a Reschke buy but with approval of Guardiola who watched him at a match and met him with his parents somewhen last spring - Bayern hijacked the buyback-clause of Stuttgart (Stuttgart bought him back and Bayern bought him from Stuttgart).
He is a young Alonso - very intelligent off the field, too. He is Pep's project and Alonso took him under his feathers. He is meant to be his successor at Bayern. He sometimes starts in the lesser matches instead of Alonso or gets substituted in for him. Pep already in the past often projected him a big career for Bayern and in the German national team.
With Badstuber out for the season, Boateng out until end of April (it seems he will come back earlier and will start running in the next days), Martinez out until mid of March and Benatia out about all of the time we did not have any central defenders anymore end of January. Since then Pep now uses 1,76m Kimmich as central defender in combination with Alaba - even in matches against Wolfsburg, Juventus and against Dortmund. And he has done a great job. Yes, he has made a costly mistake against Juve - but that was his fourth or fifth game as a central defender and the third match he started in the Champions League. But besides that he has really done great - in a new position for him for which he does not even have the body - and against big opponents.