I'd say you are right, people definitely believed that it would be easy to replace Murray in free agency, in the draft or via trade, but what happened is, most RBs signed for more than the reported low ball offer we sent to Murray (4 years/$16 million), there was a run on RBs in the draft and Peterson never became available. Now, I do think Randle can have success in this offense. He may even be better in certain areas, however, we will miss his physicality in short yardage and his dependability in the passing game as a blocker and a receiver.
And I like Williams, people can knock him for his inconsistency, but he makes a ton of big plays. But as you said, how much should we pay for a #2 receiver (fwiw, Beasley's avg cap number is $3.4 million)? Considering the money tied up else where and the future money we will need to tie into the o-line, the smart play is to have a replacement for Williams on the roster. It may result in having an inferior player, but it would free up money for another guy that may be a bit less replaceable.