I've been studying options for a while now and have been researching calendar straddles, selling high IV front month and buying back month. My simulations in TOS are giving me too good to be true estimates. I've been playing with buying more back month vs front to go from short to long gamma. These greeks I'm getting just seem to good to be true, long gamma, positive theta, delta neutral. The only risk I see is of back month volatility collapsing. What am I missing? Prices are based on buying at ask and selling at bid.