I agree, Duursma and McKercher fill needs, and with Zurhaar and TT RFA and OOC, it is a bit of insurance.
Many of our mid forwards are postionally versatile, and I still remember the Geelong teams where from week to week, I could not tell if Chapman and Stevie J were extra mids, or deep forward scoring threats. One week they would get 27 touches, and the next multiple goals from limited touches.