In a field where no one stands out, all positions were not created equal.
In a field where no one is standing out, I would give some thought towards the big picture. Worse comes to worse, we won't be able to fill either the pg or the C position internally. Which position is harder to come by on the free agent market. Which position has a trend of players being locked up before they hit free agency at a young age. Which position opening could be filled in a future draft, if we can't address it in this one.
I offer the disclaimer that I'm just going by draft reports. There is no shortage of Kemba Walker sized pgs entering the college ranks. There is also no shortage of Kemba Walker sized point guards that think offense first. The question boils down to how well he runs an offense, and what kind of intangibles he has. How much of what sets him apart makes him the kind of guy that doesn't come long very often, a true gem. It's a tough sell for me.
The euro-bigs could go bust, which is why you lean on your scouting staff. They already have the size and athleticism for the nba game, already puts them into rare company. Mix in the skill and the company is even more exclusive. Do they have the determination to succeed? Are they capable to adjust to not just bullying people like they used to? This is the kind of stuff that we can't figure out as fans. A bigmen with the right mix yields a payoff that would be much, much greater then a more easily replaceable pg like Kemba.
Teams only need to dress (or pay) one starting calibre point guard. Most pg can only play the one position. A center with sufficient skill and athleticism could cover two positions. When a team has two starting calibre pgs, there is a controversy and more often then not one is shipped out of town. We've seen this play out with TJ Ford - Calderon, and Calderon - Jarrett Jack. With bigmen, teams are happy to hang on to a third big and have them backup both front court positions. It's the fourth big (ie Reggie Evans on this time) that usually seeks a bigger payday and more minutes elsewhere. On the free agent / trade market, a teams second best pg is usually better then a team's fourth bigman.
On a rebuilding team, thought is also given to what kind of traits your looking for in a new addition given the context of the existing team. Looking at our pg position, we may stress the ability to defend other pgs, given the trouble that Calderon has. Given our lack of three point shooting, bonus points for the ability to makes shots form deep. Nothing narrows the field from a style of player perspective, we could use a shot first type or pass first, preferably both.
With regards to bigmen, we have a longer list of expectations. Since both Ed Davis and Amir are lanky, we need a C that is bulky. The center can't cover minutes at PF due to existing depth at PF and not enough at C. Since neither of those guys have established postup games, the C would preferably have that as well or the kind of style of play that indicates a preference for playing inside. Since Andrea can't defend the interior, the C needs that skillset as well as the ability to rebound for two people. We can't afford to let a player that meets even some of those expectations pass us by, since they don't come along very often.