I moved a Coulter pine the other day that had been in the ground for about 10 years +/-
It never did that well and has a trunk only about 1/2 inch diameter and probably 2 feet tall. It was usually not that healthy looking, but recently it started looking better than ever.
Digging it up, I saw that it was pretty much strangled by roots from nearby Arizona cypress and Eldarica Pine (Mondell pine). The roots were incredibly thick especially considering the other trees were about 20+ feet away (they are about 30 years old though).
I dug a good size ring about 2 feet deep around the whole tree leaving a large rootball area. Digging was tough through the roots and also because the roots were so thick that they really prevented much water from absorbing into the soil so it was pretty dry even after 8 inches of rain in the last month or so which to my mind was pretty incredible.
After I had the root ball encircled with a 2 foot deep trench, there was really no way to dig it out with a shovel because of all the roots of the nearby trees and the hard ground. So, I resorted to my rock moving tricks and picked up an 8 foot log and jammed it in the trench and used it as a pry bar to break the root ball free. The final product weighed about 200 pounds, too much for me to lift out of the hole. I used a hand size garden fork and scraped enough dirt off the ball to lighten to load to about 150 pounds and lifted it out. It was too big to fit in a 15 gallon pot so I wrapped it in a plastic bag an loaded it in the truck. I transplanted it the next day.
If it survives my transplant job, it will be much happier as it now has nothing to compete with (except gophers, but I am working on that problem!)