Tony I did 2 for 14 hours at 250. They fell completely apart trying to get them off. Yours doesn't look tied either. What temp did you run?
For a pork shoulder or Boston Butt I try to keep the smoker temp at 225 and allow it to move between 220 and 240. I want an internal temp on the Butt of 195. I don't tie it up, never had one fall apart on me but they are extremely tender, very easy to pull apart.
Do you have the fan/temp management add on? Adjustable Rig?
I don't have a temp management system, I like to do it myself. I do have a dual probe thermoter that gives me my grill temp and internal meat temp. It has a wireless unit that comes in the house with me.
I bought the egg thermometer that has the inside temp and the meat probe with remote alarm. It let me know at 3am that the temp was dropping, no idea why, but I had to get up and open it up a bit, and then it went up, had to reset. The inside temp on it clipped to the grate above the plate setter shows a good bit higher than the dome thermometer on the egg.
What happens on a long smoke is that the mound of charcoal burns out to the outside and, even though you may have enough charcoal in there, it looses some of its heat and needs more air. I had to do the same thing this weekend about 6am Sunday, added more charcoal as well.
Your dome thermometer should show a higher temp than your grill temp...heat rises. You may have had your grill thermometer real close to the one of the openings on the placesetter where all the hot air is coming around the placesetter, up to the dome and then circulating.
Have you ever calibrated your dome thermometer, if not google how to do it. The BGE dome thermometers are not the greatest.