Did my first non-league football/soccer match today with pitch side access and while it was great fun, I don't think it went as well as it could have done. My gear at the moment is a Canon 1D X Mk I and the lens I used was a Tamron SP 70-300mm f/4-5.6 Di VC USD (both bought used recently).
I was in a great position for some shots but was disappointed to find that the shots came out nothing like intended. Sometimes the focus was on stationary objects that were well outside and behind the moving action. Other times it seemed like the focus was on nothing at all and this caused a shot and save by the keeper to be completely out of focus for the 10 shots that were taken. I use back button focusing to try and maintain the focus during shooting.
My question is if this is a lens problem or a camera problem? The shot and save I mentioned earlier was right in the centre of the frame, and should have been at the strongest AF point and had players to the left and right as well and failed to find focus on any of them. I have subsequently read a review that has mentioned this specific problem with my lens so I'm inclined to think it's a lens problem.
As an FYI in case somebody is thinking this, the AI servo modes I was mainly using was the ignore obstacles (think this is 1 or 2) and the accelerate/decelerate quickly with all 61 AF points active (assuming the Tamron can use all of these points)
I have never used that camera, but maybe use a smaller group of autofocus points? I use a few at the center for birds, which is I guess slightly similar to sports.