The fact that Andrew Chafin is still available on the free agent market seems to be related to his asking price - something Ken Rosenthal noted in a recent column. He did link the Cardinals to the lefty, and I think he would be an excellent addition to their bullpen.
Chafin posted a 2.83 ERA with a 10.5 K/9 over 57.1 innings with the Tigers in 2022 and opted out of a $6.5 million player option to enter free agency. He is primiarly uses a sinker and slider combination to get outs, and is coming off two excellent seasons.
FanGraphs has Chafin projected to hit the 63 inning mark with a 3.65 ERA in 2023, which seems to be on the lower end of his projected outcomes. There is always a bit of hesitancy to hand out a multi-year deal to veteran relievers, but if the Cardinals want to take their bullpen to the next level, taking a chance on Chafin may be the best way to do that.
Considering Matt Strahm signed a two-year, $15 million deal with the Phillies a month ago, it'll likely take a bit more than that to lock up Chafin unless the Cardinals are willing to wait out Chafin's asking price some more.