"What will the Phillies do should they fail to land free agent superstars Bryce Harper or Manny Machado?" This is a common question around baseball.  As of now, neither player is signed.  The Phillies are headed to Las Vegas to meet with Harper on Saturday and preparing a second offer to Machado.  But the Phillies appear also to be making contingency plans.

According to J.P. Morosi of MLB.com, the Phillies are looking at an alternative third baseman option in Mike Moustakas:

The Phillies and White Sox are monitoring Moustakas' marketplace, sources say, and each club is interested in making him an offer if its preferred free-agent third baseman, Manny Machado, signs elsewhere.
It's easy for the Phillies and White Sox to remain in touch with Moustakas, since his agent -- Scott Boras -- also represents Bryce Harper, in whom both clubs have interest.

Morosi also notes that the Phillies would then attempt to trade Maikel Franco should Moustakas land on the Phillies.

A left-handed bat, the team who lands Harper might not also add Moustakas.  Last off-season Moustakas rejected a qualifying offer from the Kansas City Royals and failed to find a home.  Perhaps turned off by attached draft pick compensation, Moustakas ended up having to sign a one-year, $6.5 million deal with the Royals.

Moustakas was traded at the July 31 trade deadline to the Milwaukee Brewers.  Ahead of the deadline, the Phillies were reportedly interested in acquiring Moustakas.  Moustakas batted .251 and hit 28 home runs, driving in 97 between the Royals and the Brewers.