more detailed explaination

The 2011 Collective Bargaining Agreement gives a major advantage to teams writing these poison pill contracts. For salary cap and luxury tax purposes, only the average yearly value of the deal is counted. But a team matching the offer does not get the same benefit.

For example: the Houston Rockets offered identical contracts to Knicks guard Jeremy Lin and Chicago Bulls forward/center Omer Asik. They deals will pay roughly $5 million in years one and two and $15 million in year three. For the Rockets, those deals will count as roughly $8.3 million contracts each year, for cap and tax purposes. If the Knicks opted to match, Lin's deal would count at its actual value. That $15 million cap hit - combined with the contracts of Amar'e Stoudemire, Carmelo Anthony and Tyson Chandler - would have come with a staggering luxury tax bill.

Now bench should understand why Rockets use poison pill: they wanted Lin, not that they wanted to poison kincks hehe