Really only two things that will just make your good images better:
1) get as low as you can. At a minimum sit down on the edge of the track; we used to shoot a lot of stuff out of the (empty) steeple chase pit or in some cases lie down on the track (including at an IAAF grand prix meet);
2) watch the backgrounds. Not much you can do about the shot put picture for the shot you took, but I'd be curious to know what the background was like for the LJ shots head on or from the other pit corner.
The shot put area was surrounded by the athletes who were about 6 to 8 ft behind the thrower from any angle I had bodies in the background. I chose this angle due to the fact that the background behind the thrower, where the other participants were standing were on a slight elevation. Don't know if it was the right choice or not.
As for the long jump pit, I tried to get as straight on as possible, but with the least going on in the background.
If I was directly straight on, remaining of the bleachers that you see in the background on photo no. 3 are present.
If I moved further to the right of the pit, the second long jump pit participants as well as the residential development behind the fence would be in the background.
If I moved to the left of the pit, more bleachers, the back of the snack bar and other participants awaiting their turn to jump.
For the long jump pictures, I was kneeling and just to the right of the pit, hoping to get the sky in the background like some of photo no. 4. But as I look at it, the trees and participants take away from it.
The relay photo was taken on the outside edge of the track and standing.
I understand your reasoning on trying to to get a cleaner background, but IMO, long and triple jump look much better head on. Having even an edge of the pit also adds to the shot. Shooting from the side works in some environments, but the angle you have here is neither one nor the other, making it look like a mistake, not a deliberate choice. Given your description of the surroundings, I would probably opt for straight on. The bleachers are not ideal, but if you can get them to cover the entire frame, they may look more like an oof graphic element and actually be less distracting.
The other thing you can do with LJ and TJ when backgrounds are horrific (and they aren't that bad here) is to shoot low with a very wide angle from the side. All going well, you get that mythical Sports Illustrated "sense of place" photo.
Shot put is a consistent pain at most meets. Either the other athletes seem to be waiting in the circle with the thrower, or your stuffed up against parked cars/walls/fences. Even at major international meets where you can really nicely frame from the outside of the track to the infield circle with a long lens you still have the problem of the field officials and infield photogs looming in the background.
