I'd have bitten the bullet and traded Mayer + Tolle for Marte. (I'd expect a prospect back, but I'd do the deal without one.)
We are in a 3-5+ year window, right now. KMarte could start a steep decline at any moment. I fully understand the gamble, but Mayer & Tolle are gambles, too.
Marte is a switch hitting power bat, who also gets on base enough and plays 2B pretty well. We could have still done the Durbin & Contreras deals, and even IKF would be okay, but we'd probably have to save some money to pay for KMarte. Maybe deal Sandoval with no IKF.
Of course, trading Duran and his $7.7M AAV might have been done.