Football Outsiders, which does rank DBs (but as part of their premium database) has the Packers defense ranked 21st versus other teams #1 receiver.
2nd rank against #2 WR
19th against other WR
4th against TEs
4th against RBs
Shields was the 13th ranked CB and Hayward was the 15th in adjusted yards per target. They were 19th and 20th respectively in success rate. Hayward was 3rd in target rate (who was getting picked on) and Shields was 18th.
So perhaps Hayward was solid but unspectacular, which is why they wanted to re-sign him but not break the bank.