49ers signed CB Tramaine Brock to a four-year extension

San Francisco 49ers cornerback Tramaine Brock has signed a four-year extension with the team. The deal is worth $16 million overall and includes $7 million guaranteed. Brock was playing under a one-year $1.323 million deal and would have been a free agent this summer.

Pro Football Focus graded him out as the No. 18 overall corner and his four interceptions are tied for second best in the league. Brock replaced Nnamdi Asomugha as the 49ers’ nickel back in Week Five. He will get his first start on Monday Night Football and the 49ers clearly think he has a future.

“I think the change comes in that he went from not playing to being in the nickel, which is a part-time job where you’re in and out and you usually get a break of at least two or three plays or longer depending on the game you’re in,” 49ers defensive coordinator Vic Fangio said, via CSN Bay Area. “And now the change comes, it’s amped up another level. He’s in there every play.

“He’s just got to be ready to play every play not knowing he’s got built in breaks when we’re in base like he had for the first however many games he was playing. There is a change, but it’s just got to be a mental adjustment for him.”