I'm trying to figure out where each side got its number.
Ellsbury just settled for ~ 3.5 times his last year salary ($8MM) in his 2d arbitration year, and he had a better year than Morse. That would support the Nats. Alex Gordon, in his 3d year of arbitration, flied at $5.45 MM, with KC at $4.15MM, coming off a better year than Morse in terms WAR, and steals (17) but a worse year in terms of HR (23) and RBI (87); arbitrators look at traditional stats (batting average was a wash - .303). Gordon is coming off of a $1.4 MM prior year.
looks like it is line with the raise Gordon is getting in terms of % jump, and arguably Morse is coming off a worse year.
These settlements seem pretty far off the FG rule of thumb that a player gets about 60% of a free agent's $/WAR in the second year of arb and 80% in the 3d. That would be $3MM per projected WAR for a 2d year player and about $4MM for a 3d year. No way that works in these cases. that would have gordon at 1 - 1.25 WAR and Ellsbury at 2.7 WAR.