CBS still has the highest-rated (The Big Bang Theory) and most-watched (NCIS) shows on television, which is par for the course for the network. That means it was merely a matter of pruning the schedule by getting rid of the weak and bolstering the strong with new shows headlined by big names. That's pretty much what CBS has done for last several years, and it won't change this season.
CBS' 2017-2018 SCHEDULE
RENEWALS AND PICKUPS