Yes, naively the connection looks like head impacts. The high rate of concussions in soccer is not widely appreciated, despite being over half the rate of American football (about which a lot more has been written).

https://storelli.com/blogs/the-storelli-blog/soccer-concussi....

https://journals.lww.com/cjsportsmed/Abstract/2001/10000/Con...

From the first link, here is the ranking of concussion rate:

1. Rugby (4.18/1,000 AE) 2. Ice hockey (1.20/1,000 AE) 3. American football (0.53/1,000 AE) 4. Lacrosse (0.24/1,000 AE) 5. Soccer (0.23/1,000 AE) 6. Wrestling (0.17/1,000 AE) 7. Basketball (0.13/1,000 AE) 8. Softball & field hockey (0.10/1,000 AE) 9. Baseball (0.016/1,000 AE) 10. Cheerleading (0.07/1,000 AE) 11. Volleyball (0.03/1,000 AE)

> Athletic Exposure (AE) is defined as one athlete participating in one game or practice.