So I did compare the performance of NBAdraft.net and draftexpress.com in 2013...
That's my result:
number of picks correct:
NBAdraft.net - 4
DX.com - 3
Bleacherreport - 1
number of predictions close by 2 places(e.g. predicted 3, picked 1 through 5)
NBAdraft.net - 12
DX.com - 12
Bleacherreport - 9
mean error per prediction(in draft slots)
NBAdraft.net: 6.5333(undrafted projections on Andre Roberson and Solomon Hill counted as 61st pick) - filtering out big misses(Every false prediction at least 15 slots wrong: Roberson, Hill, Nedovic, Goodwin) cleaned up mean: 2.962
DX.com: 4.766 - filtering out Goodwin, Nedovic, Hill: new mean: 3.444
variance
NBAdraft.net: 138 and after leaving out the same misses as in the mean calculation: 13.962
DX.com: 45,433 and 19 after cleaning up
So you can say that NBAdraft.net is considerably more inconsistent in picking the range of a player and they did more HUGE biffs and an equal amount of predictions very much off(more than 10 draft slots away)
Another thing that caught my mind is that DX sometimes had the team but was wrong on the pick they used(Predicting Andre Roberson to OKC with the 32nd instead of 26th, which was also OKC's) There were more of these kind of things but I'm too lazy to revisit it. Both services were comparably off on the lottery picks. If anything DX was slightly less off, but really we're talking inches here. But outside the lottery it becomes obvious that Givony is better connected with league sources than the guys running NBAdraft.net, whose performance really dropped, while Givony obviously had some insider infos he used in his final edition.