Plug plants/Jiffy 7s

I received some wave petunias plugs from T&M today, they came in small open sided firm plastic containers they are supplied in strips of five, the concept is quite good, but when the plants were removed for potting on they all had a mass of roots at the base and all shaped in a square, personally I pull these roots out to loosen them as I think shaped like that they will just continue winding like that, I was successful with some, others the roots broke, the root plugs are about the size of my pinky nail, so rather small for trying to do delicate work on them