Hedger -- You're right if they had sold equal number of puts as they bought calls, but what they did, as you mention, was use part of the credit to buy long puts. It's called a Put Ratio Backspread:
http://www.stock-option-trading.com/ Put Ratio Backspread – Sell higher strike puts and buy a greater number of lower strike puts (1 to 2 or 2 to 3) in a market with a forward volatility skew where you anticipate a sharp price decline with increasing volatility. Look for even or net credit trades where possible.
Maximum Risk - Limited to # short puts X strike price difference - net credit or + net debit Maximum Profit - Unlimited on the downside below the breakeven, limited on the upside to the net credit if any Upside Breakeven = Higher put strike price - net credit or + net debit Downside Breakeven = Lower put strike price +[(strike price difference X # short puts)/(# long puts -# short puts)] + net credit or - net debit
"Also it is not clear that they bought excess puts in that the 8000 puts may have been a totally separate transaction."
If you consider that the QQQ Jan 45 puts had a total of 46 contracts trade in the past 10 sessions, it's highly unlikely that the thousands of extra put contracts today were all an unrelated transaction.
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