That's certainly not a slam-dunk statement about the FA 1B options. It was true in 2017.
Career --- 2017 --- 2018 Steamer
Moreland - 25.3 PA/HR, .439 SLG --- 26.2 PA/HR, .447 SLG --- 22.6 PA/HR
Morrison - 27.5 PA/HR, .433 SLG --- 15.8 PA/HR, .516 SLG --- 21.6 PA/HR
Alonso - 42.8 PA/HR, .407 SLG --- 18.6 PA/HR, .501 SLG --- 27.9 PA/HR
Duda - 22.4 PA/HR, .457 SLG --- 16.4 PA/HR, .496 SLG --- 18.5 PA/HR
Hosmer - 34.6 PA/HR, .439 SLG --- 26.8 PA/HR, .498 SLG --- 24.7 PA/HR
Adams - 24.7 PA/HR, .469 SLG --- 18.4 PA/HR, .522 SLG --- ?
The only one I'd be confident in saying that about is Duda (whom I would've preferred in a vacuum). You're paying for 2017 while wholly banking on it repeating itself in the case of any of the others except Adams, who is strictly a platoon player.