Question: How do you replace a ~3 WAR second baseman/utility man making 5 million a season?
Answer: With a replacement level infielder for ~5 million over two years.
I'm not a fan of the Miles signing, as you can tell. The Cubs may or may not attempt and deal for Jake Peavy, if they do, and they include Mike Fontenot or Ronny Cedeno, that's one thing. However, signing Aaron Miles for ~5 million is an awful Plan B. How awful? Miles WAR since 2003:
Throw 2003 out for small sample size and you have, on average, a ~0.2 WAR player, and that benefits heavily from a fluke 2008. In seasons in which he isn't riding unsustainable BABIP and LD rates, Miles is a replacement level middle infielder without a great (or even good) glove and with a poor bat. The Cubs could've thrown a dart at their (or any) Triple-A roster and found a player with similar traits for less than a million dollars. Heck, what about Andres Blanco?
Heaven forbid if the Cubs give Miles 400+ plate appearances.