I don't think it is. In my opinion, there are three main reasons to deal away veteran players:
1. Payroll constraints
2. Poor team performance
3. Bad farm system/drafting
We're a 90+ win playoff team with payroll space and a good player development system. Everything is set up nicely for us.
If we apply a regular decline curve to both guys, they still project for 10.5 WAR each in the next 3 seasons. We've already got Martin, Tulo, and maybe Donaldson on long term deals, so the benefit of those wins is immense. If you want to remain a playoff team, we'd just have to replace that production somewhere else, maybe at an even higher cost.
I guess what it boils down to for me is, where's the need? We have young pitching and some other resources to bolster it. I'm not against a long term outlook, but we can also keep winning in the process. I don't think that's a pipe dream.