By virtue of missing out on Talib, the Niners instead signed Richard Sherman on Saturday to a three-year deal worth up to $39.15 million, per ESPN's Josina Anderson.
Phillips served as Talib's defensive coordinator with the Broncos in 2015 and 2016, while Talib played under Belichick with the Patriots in 2012 and 2013.
In acquiring Talib, the Rams have a brand-new starting cornerback tandem for 2018, as they also landed Marcus Peters in a trade with the Kansas City Chiefs.
The Rams surrendered a 2015 fifth-round draft pick for Talib, who can become a free agent after the 2019 season.
Talib's reported refusal to go to San Francisco may have worked in the Niners' favor given the NFC West rival Seattle Seahawks released Sherman shortly thereafter.
Sherman and Talib have resumes that compare favorably.
In seven NFL seasons, Sherman has won a Super Bowl, made four Pro Bowls and been named a first-team All-Pro on three occasions.
Talib also has a Super Bowl win to his credit in 10 seasons to go along with five Pro Bowls and one first-team All-Pro selection.
Sherman has 32 career interceptions to Talib's 34, although Sherman has played in 30 fewer games.
The biggest concern regarding Sherman is the Achilles injury that cost him part of the 2017 season, but he expects to be ready for training camp, per Schefter.