The 5th starter is really looking like the lynch pin for this teams success. As the roster stands now I believe they can win a first round playoff match-up but would not expect anything more. An upgrade to the 5th starter is going to have to happen in order to push deeper in the playoffs.
The current options KO,JJ, and Amir all play different roles. KO is the most talented of the bunch and should be starting however he is also better served as the first big off the bench. JJ gives the starters a small ball look with JJ being more of a SF then a PF this isnt a bad thing however he isn't talented enough to compensate for the lack of rebounding he brings. Amir in theory gives a bigger more defensive orientated look but appears to be aging himself out of the rotation.
DA and BS need to figure out which niche is better to fill with the 5th starter defensive traditional big to fix rebounding issues or a combo forward whose talent compensates for the lack of rebounding.
possible fits
traditional big: Noel (talked about at length), Bogut (talked about at length)
Combo forward: Gallinari (was rumored in the past), Gay (always in rumors), Mirotic (coming off the bench and having a down year)
Talented but not perfect fits: Monroe (alot of talent just not a modern game), Faried (alot of holes in his game but brings energy and rebounding)