i was running some breakdowns on this:
(assuming we are working with 18 slots only since: ilvl 28s for mastery are needed outside of the 3-socket TBC pieces)
for BGs or 2s arenas:
9 talas + 2/2s = 18 agi / 72 stam
9 talas + 3s = 27 agi / 54 stam
for 3s arenas:
2/2s = 36 agi / 36 stam
3s = 54...