A lot of tele zoom lenses have "MACRO" written on them and it's sort of meaningless. They might better be called "close focusing", not truly "macro". It's just marketing hype to sell the lens to people who don't really know what macro is. I'm not aware of any "true" macro lenses that are 70-200. Nearly all "true" macro lenses are primes (not zooms) such as 60mm, 100mm, 150mm, 180mm.
So the lens should have been able to shoot soccer just fine. A big part of the problem is probably with the "user". It takes a lot of practice to shoot sports. You have to learn to anticipate the action and time your shots (alternative is to set your camera to shoot 8 fps and end up with thousands of images, then sit at your computer editing out the bad shots, which will be a high percentage).
Yes, I agree, stopping down to f4 or f5.6 would have helped reduce/minimize focus error.
Also, I'd use Center AF Point only and AI Servo, as you did. But I also use Back Button Focus
for sports shooting.
Also, look at the lens. Is it an HSM model? That's Sigma's version of Canon's USM, and helps the lens focus a lot faster and more accurately. I am pretty sure there have been a bunch of different Siggy 70-200/2.8 versions, maybe some of them are not HSM? I really don't know. My Canon 70-200 has USM and is easily my most used lens for field sports and similar.
Mainly, it takes practice... and soccer is tricky because the direction of travel changes abruptly and a lot. You will have more missed focus shots with that type of action, no matter what lens and camera combo you use. Besides practice, there's also a matter of having "reasonable expectations".