Because maybe they like Eovaldi or the payer we add to the deal more, or we get a 2Bman or CF not a pitcher, and that team has a glut of players at the position we need. (Then, we fill the pitching gap via free agency.)
Let's say a team really likes Beni and thinks Eovaldi is helpful, too. They just don't want to pay $17M. If they think Eovaldi is worth $10M, they may dump $7M back at us at a position we need. If it's a pitcher, the added value of Beni gets us a better, cheaper or more durable pitcher than Eovaldi. If it's another position player, the money saved could be used to upgrade other gaps.