Meanwhile, Frank Gore, Michael Crabtree, Ray McDonald, Chris Culliver and Perrish Cox left the club during free agency, while the 49ers also overhauled their coaching staff as Jim Tomsula replaced Jim Harbaugh as head coach.
Dockett was one of the few players to join the 49ers, but he has insisted that the club will still be a success in the 2015 campaign.
He said on Twitter: "Don't ask me about who's retired and what's going on with football this and that.... We will still WIN! Just watch! #savage #adversity.
"The story in the end will be that much better!!!!"
The 49ers missed the playoffs for the first time in three seasons in the 2014 campaign as they posted an 8-8 record.