I have only recently smoked chuckies because of the good results I'm seeing on the interweb.
Adrenaline puts out a heckuva chuckie...HOS does,too.
I try to follow their technique and get great taste and texture.
On this attempt, I'm thinking that smothering the meat with the vegetables slowed the cooking and didn't allow the connective tissues to break down.
I pulled mine at 170 and wrapped tightly in foil with a little beef broth added. I guess this allows more heat and moisture to hit the meat than when it is covered with vegggies.
Mine turn out more like brisket that a chuck. I'm just a backyard jack, but folks here have helped me out a lot.