At leat Sinkhole helps a matchups(Zoo) where it keeps cats and apes small and form a lock with Stifle and Wasteland, where the opponent only got a 1/1 critter. Spell Pierce helps Control( good winnable) Combo( can't be lost). If you want to replace Sinkhole with something it would probably be creature removal like Smother or Pulse. But than your mana-disruption is just as good as Tempo Thresh and you will give up your control matchup. In fact at that moment it's probably better to play Tempo Thresh.
- Benie

