This happened to me in two games/two days.
I was looking in the internet about that but couldn't find how shirt pulling can cause such injuries - some photos
Click image for larger version.  Name: pull shirt 1.jpg  Views: 36  Size: 28.1 KB  ID: 46908

Click image for larger version.  Name: pull shirt 2.jpg  Views: 37  Size: 34.1 KB  ID: 46910

Click image for larger version.  Name: pull shirt 3.jpg  Views: 36  Size: 29.1 KB  ID: 46912

even with this, I cannot understand how a player can have a serious injury
Click image for larger version.  Name: pull shirt 4.jpg  Views: 37  Size: 21.4 KB  ID: 46913