Titans signed Butler on March 13 of 2018. The pats traded for JMac a couple of days later.
Butler had a 6 mil cap hit last year. Its 13 mil this yeat.
Jmac had a 3 mil cap hit.
Malcolm Butler statistically worst corner in NFL so far, so maybe Belichick was right
Titans signed Lewis March 15, 2018. Pats signed Hill one day later at almost 1/4 the cap hit.. Hill got injured and the Pats drafted Michel. So Last year:
Michel 981 YFS 480K salary 1.75 mil cap hit
Lewis 917 YFM 2 mil salary 4 mil cap hit
Pats tried to keep Soldier with a very solid offer. The details of the Giant offer and where Nate wanted his family ultimately made the Giants the winner. 1.5 months later the pats signed the best LT in Football
Then they won the SB
So, I am not sure what your "no replacements in sight" comment is about when 2 out of the 3 were replaced a couple days later.