Sprinkle chicken evenly with barbecue seasoning; gently rub in with your fingers.
Grill chicken, covered, over medium heat 10 minutes, turning once halfway through grilling. Meanwhile, remove 1 Tbsp. zest and squeeze 2 Tbsp. juice from lemons. Set zest aside. In the foil pan combine the lemon juice and the next six ingredients (through olive oil). Place foil pan on the grill rack. Grill, covered, until tomato mixture is boiling. Transfer chicken to the foil pan and nestle drumsticks down into the tomato mixture. Cover and grill 25 to 35 minutes or until chicken is no longer pink (180 degrees F), turning chicken once halfway through grilling.
Season tomato mixture to taste with pepper. Sprinkle with parsley and reserved lemon zest. If desired, serve with hot cooked polenta.