I am best at shooting soccer? Why? Because I coached it for 19 years, and still do. I know where the play is going to develop before most of the players do. And I am there, waiting for them with the camera. I played numerous sports at different levels. Basketball, tennis, soccer, golf (badly), volleyball, wrestled, etc. Having a good understanding of SPORTS allows a photographer to get the moments other's usually miss.
I would be remiss in saying the gear doesn't matter. If you can't get the shot because the gear won't let you, then the gear is a limitation. For outside, day time sports, we have LONG passed the technical issues of the gear being good enough. Indoors under poor light and WITHOUT the benefit of strobes, well that's a bit more dicey. And outdoors under the lights is hit or miss depending on the lights.
The truth is, I could take my D200 and get 80% of what I get now on the D3s or the D800. But it's that elusive goal of trying to produce more keepers, more spectacular work that keeps me going forward with the gear. I suspect it's the same for most.
I was shooting birds today at lunch. With my 300/2.8 and a 1.4x tele, and wishing I had a 600mm and a 2x tele!