If we're going to run stuff similar to what we have, with the same guys on the court...
Then I'd say dump it down to Trayce on the right block, and then space/clear out. Let him work, and try to get middle. And if people collapse on him, hope that he makes the right read and passes it well to the right person.
If this question was open to them playing anyone, and running any style offense...I'd say put Trayce and Race in each short corner. Then do some sort of dribble handoff action with Xavier and Trey, and then have Parker spotting up opposite wing.
That should give Xavier or Trey, whoever ends up making the move towards the basket, plenty of room in the middle of the court to get into the lane. At that point, if there's help off either big, dump it down to them. If Parker's man collapses instead, kick it out to him. If there isn't much help, both Trey and Xavier are capable finishers at the rim, and both are decent free throw shooters should they draw fouls.
You could insert Tamar for Trey in this situation too. I just think Trey is a little stronger right now with the ball. Tamar does bring more of an outside shooting threat advantage though.
If and when Rob comes back, he'd be another guy to use in those dribble action roles.
We don't have a single player on our team that we can "1-4 flat" with and have any confidence they'll be able to make winning plays.
