I find it difficult to imagine what this might mean, never mind decide whether or not the "to" is important.
Please tell us where you found this sentence, and make sure you include some context so that we know what kind of "aerial balls" these are.
I wrote this thread in a hurry. I should have, indeed, put it in proper context.
It has to do with football. Someone was ranting about a particular football team's centre-backs, in the comments section of an English newspaper. However, said someone had words of praise for their ability to defend aerial balls (yeah, those, not other, balls...). It read like: "Yes, I agree with the above comments. Those two can't take a defender running at them and are slow. The only thing these wasters do well is defend aerial balls.".