Definitely want both bats in the lineup somehow. The question becomes which defensive arrangement costs the fewest runs. If the WAR positional adjustments are not total nonsense, Westburg at 3B and Mayo at 1B or RF would be preferred. His arm might make RF the better choice of the two.
The Apple people bring up Christian Walker was an Oriole. I don't know the exact details but someone posted that the management looked at Mancini and Walker as kind of the same player and they liked Mancini more so they let Walker walk. Then we let Yaz go to SF. Kind of odd that a team desperate for talent let two decent guys get away.