They need at least one veteran. The price for a top rotation guy might be too high. A back end guy who pitched well last year would be at least a decent backup plan
Williams will be 33 and only made 13 starts. The rest of his time as a starter is a bad #5. Sorry, ain't good enough. If that's the plan, then just sign Goldschmidt and Yoan Moncada, and punt another season.
They have to get someone that can be reasonably expected to provide 25+ starts with a sub-4.00 ERA.