I voted Seth because this team really needs an elite 3-point shooter to be successful long term. If Seth can't find his stroke consistently and be that guy then I'm not sure this team can succeed in the playoffs.
Edit: I didn't look at this until after I posted the comment, but so far this year Seth is 14/28 (50%) in Mavs' wins and 3/19 (16%) from 3 in Mavs' losses. Correlation does not equal causation, but I think this helps affirm my belief that they need Seth (or somebody outside of Luka/KP) to hit 3s at a high rate in order to be successful. If not, those beautiful passes from Luka go to waste.
Edit: I didn't look at this until after I posted the comment, but so far this year Seth is 14/28 (50%) in Mavs' wins and 3/19 (16%) from 3 in Mavs' losses. Correlation does not equal causation, but I think this helps affirm my belief that they need Seth (or somebody outside of Luka/KP) to hit 3s at a high rate in order to be successful. If not, those beautiful passes from Luka go to waste.