Nice looking shots, thanks for sharing. Pentax appears to have really hit a home run with the K-1. But your experience here shows that it's not the ideal camera for sports. The K-1 does about everything well, but 4.4 fps is very limiting for many sports situations.
The fact that you have to throw out over half of your sensor's resolution in order to get the fps that you need is very unfortunate. I shoot a lot of sports with the K-5iis, and I have had situations where I needed to switch to AF-S in order to get closer to 7fps instead of the ~ 5 fps I get with AF-C.
I'm not one of those that have been waiting for FF with Pentax, but after seeing the incredible reviews and results from people, it has me wanting one. I am hoping that Pentax follows up the K-1 with an upgraded model that has a higher fps rate and a more action oriented AF system. The only problem with that is that I probably wouldn't be able to afford it.
You seem to working well given the limitations. I'm sure you will find yourself switching between situations where you work with the 4.4 fps and use the whole sensor, and times where you need the higher fps and use crop mode as you have done here. I'm very interested going forward with seeing how people handle sports situations with it.