Looking for Copper to Versus Into Seasonal Weakness

Copper has been rising steadily since the later part of March but appears to be running into resistance at the current level. On June 10-11, the front month contract formed a bearish engulfing pattern which usually is a sign of weakness. In addition, Copper is entering a seasonably weak period which gives me added confidence that weaker times are ahead. To trade this, I'm looking to sell the Copper (U20-Z20) calendar spread. This trade has hypothetically profited in 14 of the last 15 years when sold on 6/29 and bought on 8/4. The average profit to draw-down ratio is very strong at 242% while the average best profit is 4.6 time the average worst loss. I suggest a limit near the ($1.70) range on entry,