To put is some $ terms. Gray is going to a roughly 5 fWAR pitcher this year. If he does that for 4 years at $8 million/WAR that is a $160 million value. Let's overshoot his arbitation salaries and go $.5, $4, $10, $20. These numbers are way to high, but that is $34.5 million over 4 years. His excess value is $125.5 million. Hamels brought back 3 top 100 guys with maybe half that excess value.
And you need to discount that value by at least 25% based on the breakdown rate of pitchers.