I'd kinda agree with John (although maybe a bit more diplomatically-Lol). Looking at these shots doesn't show me any real issue. I would make a few comments though. The Egret(?) was shot at ISO 800 f22 and 1/350th @200mm. So these settings are going to cause issues.
1) you need to shoot at middle f stops for best results with this or most any lens. When you stop the lens down this much you get image distortion from the small aperture. Each lens has a "sweet spot" which is generally in the middle ranges. Wide open or stopped down will often be much softer.
2) ISO 800 is fine when you're trying to get more out of a dimly lit scene or get more speed out of the setup to get action shots but here you don't need it. Shoot at the lowest possible ISO you can all the time. If you ever shot in the 'good old film days' then you'd understand the vast differences from a slow speed film and a high speed film. The slower the speed the less grain and higher detail you will get in every shot. These cameras do a very good job of reducing noise at higher ISO's but when you crank up the sensitivity something is going to suffer - detail.
3) Shooting at full zoom. If you read the reviews of the vast majority of lens reviews they will almost always say that shooting at the extreme ends of a zoom will soften the images. Pull back 10-20 mm and the image will sharpen up.
Combine the above and that will most likely help fix the results you are experiencing.
Another suggestion is to turn off the camera's noise reduction for daylight shooting. Use it when you are taking longer exposures of more than 2-5 seconds and longer. Also if you want the best of your camera and lenses, shoot in RAW. Jpeg's are fine but a RAW image is sharper and has a wider dynamic range. You can sharpen and do much more with a RAW image in the computer to get the results you want. Think of it as the negative in film.
Shooting technique: learn how to use hyperfocal shooting and also depth of field as well as shoot with a tripod or monopod when you can. for high shutter speeds it's less necessary but you will see a difference when the camera is more stable. When hand held, hold the camera with the right hand in the side of the camera and cradle the bottom of the body/lens with both elbows tucked into the sides of your body and shoot between breaths. All of this will improve your shooting technique and results.
Have a read of the following:
Depth-of-field explained Hyperfocal Distance Shutterbug: Sharpen Your Image
A series of articles on Photozone;
Photography Techniques
and a good index of articles from the Luminous landscape:
The Understanding Series table of contents
So take some pictures of a static subject just as you have the camera now. Then set up a tripod or some other way of stabilizing the camera and adjust the camera for the best settings. Take some pictures at 75, 100 and 150mm. Compare the results and I think you'll see an improvement.
If you think this is all too much then bear in mind that these things apply to all cameras and brands including film. Of course some very expensive lenses will change some of the issues and almost eliminate others but generally the above is true for most of us.