I am of the belief we need another top-end starter to get over the hump finally in 2018. I don't think we need to add much of anything to win the NL East again. However, as many have said, Gio can't be trusted in the postseason. I also suspect he's much closer to the 2015 and 2016 Gio in 2018 than the 2017 numbers he put up. I don't expect to be able to add another #1 in the mold of Max and Stras, but we need somebody who you feel good about pitching in a postseason series. Roark hasn't really had a fair shot at that role, but I'd much rather him stay in his slot as the 4th starter we may or may not use in the postseason.
To me, that is the top priority and first order of business, other than perhaps trying to extend Harper. Beyond that, it's minor tweaks. Looking into an upgrade at catcher, although I don't think that would be nearly as helpful as adding another top-end SP. Rounding out the bench and bullpen and perhaps adding SP depth to compete for the #5 spot come last.