Preheat oven to 400°F. If using the grill, heat to medium-high and oil the grates.
Fill the injector with 2 ounces of Stubb's Texas Butter Marinade and inject it into the thickest parts of two of the breasts, injecting into two different spots if possible. Refill the injector and repeat with the remaining two breasts. (This step can be done up to a day ahead of time.) Place three sage leaves on the top of each chicken breast, then wrap each breast with two slices of bacon.
Heat a large skillet over medium heat and pour in just enough cooking oil to lightly coat the skillet. When oil is hot, carefully place the chicken breasts in the pan, top side down. Let the top sides of the chicken breasts cook for at least one minute or two and don't move them. When lightly browned and the bacon is slightly crispy, flip to the other side and cook for another minute. If the pan isn't large enough, sear two at a time. If using the grill, use the same method -- searing each side until just golden-brown.
Place chicken breasts on a baking sheet tray, top side up, baste with the extra marinade, and bake for 15 minutes or until their juices run clear. If grilling, turn heat down to medium, close the lid and cook for about 15 minutes. An instant-read thermometer inserted into the center should read at least 165°F. Let the chicken rest for at least two minutes before slicing and serving.