Complex sentence: Annotating for Chessbase, David Navara wrote that Carlsen deserved the title, as he has been the number 1 player in the world for many years, but also that Karjakin deserved credit for successfully showing that it was possible to compete on even terms with Carlsen.
Split into simpler sentences: Annotating for Chessbase, David Navara wrote that Carlsen deserved the title, as he has been the number 1 player in the world for many years. However, Karjakin deserves credit for successfully showing that it is possible to compete on even terms with Carlsen.