I don't think 142 is a problem in terms of efficiency. But if the temperature and wetting of the grain were uneven that could definitely be a problem. this is not a huge amount of grain for a BIAB but it is a pretty big grain bill. When I do big stouts, and especially If I am doing over 5 gallons at a time, I use two bags, each of which fill about half of my keggle. That way I can actually lift the damn thing when it is time to pull the grain. Also helps with wetting and stirring. I definitely think you are better off adding the grain to the bag in the pot. Much better wetting. I didn't notice whether you did a sparge or a mash out but both of those things help, especially with a big beer.
Hope that helps.
Hope that helps.