In bowl, mix together olive oil, lemon juice, cilantro, garlic, oregano, Adobo, cumin and red pepper flakes; transfer to large zip-top bag. Add chicken; turn to coat completely. Transfer to refrigerator; marinate at least 2 hours, or up to 24 hours for best results. Bring chicken to room temperature 30 minutes before grilling, discard marinade.
Heat grill to medium heat. Add chicken (skin side-down) to hot, greased grill grates. Cook until well browned on skin side, (about 10 minutes). Flip chicken. Grill until cooked through (internal temperature will register 165F on quick-read thermometer when inserted into thickest part of meat without touching the bone), about 15 minutes more.