Of course you can just simulate through a season and almost assuredly get at least one of these, but to do this in about 5 minutes:
Start a new dynasty with current rosters. Set your team direction as Rebuilding. This includes an objective to sign an 80+ rated Free Agent.
Go to sign a FA; Eric Maynor is rated 80 overall- sign him, and the achievement will pop. I was able to sign for 1 year at mid-level exception using the Lakers.