well to those first-timers who clear the written part AND the interview but miss allocation, it does appear a tad unjust (& terribly frustrating) that the ones who have prior experience of competitive exams (PCS, SPSC, mostly CSS) get better score/positions...(thanks to previous exposure & awareness of their strengths & weaknesses)
AND admittedly, the concentration of such um
dab hands 
is increasing in the top 100.
for instance lets consider the example of CE-2011 result..many er non-first-timers
1. 26 MIAN MUHAMMD MUMTAZ HAYAT MANEKA (37th CTP officer)
2. 16 ARIFULLAH AWAN (KPK PSC)
3. 22 MUHAMMAD USMAN KHALID (CSS 200X (presumably)
4. 28 RAFIA HAIDER (CSS)
5. 70 NASRULLAH (CSS 2010)
etc
in CSS 2010 exam too, there were many such examples. Officers from 37th & 38th CTP improved their groups.
the second position holder was a PCS/PMS officer
BUT all this just adds to the competitiveness of the exam
without making it unfair (or so i think)..
so lets not begrudge them their hardwork & success
