The thing some of you are forgetting is that Boras represents both Harper [ a guy the Phils want very much] and Keuchel [ a guy they want on a shorter deal.] Boras knows this as well as the Phillies do.
Do't think for one minute that Boras wouldn't suggest that a 3 year deal for Keuchel would certainly go a long ways towards finalizing a Harper deal. Now Boras can't demand, he can't threaten, he can't go that far.
But one of the advantages to representing so many players is that he is often able to cross over from one player to the next for his goals and purposes.
He has actually done this twice to the Phillies that I am aware of...both involving JD Drew and Ed Wade. In December of 1997 when the Phils were talking to Boras about Drew, he changed the subject to a 2nd baseman he was trying to find a job for..Mark Lewis. He theorized that getting Lewis a job would sure establish a good will gesture for later on and his other clients.
Phils signed Lewis and gave him the 2nd base job for 1998. Then in May of 1998, Wade contacted Boras to try and re-open the Drew talks. Boras quickly changed the subject to a Phillie prospect named Carlton Loewer and how Boras sure would "appreciate" a good will gesture again by bringing up Loewer since he was doing well in Triple A. Phils called Loewer up a few days later, he made his debut that Sunday [ a win]...and of course Drew never signed.
Boras has certainly used this tactic well with Washington, my gosh I believe at one point 10 or so players from the 25 man roster were Boras clients. There was even a half joking suggestion that Boras was in some respects more owner of the Nats than Lerner was.
I believe its quite feasible that if the Phils sign Harper, we might just see Keuchel or Moustakas [both players of need and Boras clients] becoming Phillies soon thereafter.