I don't know how boxers are supposed to look, so perhaps this is intentional. The first photo, because of the tilting line in the background makes him look unbalanced. His shoulders are higher than his hips, but if you tilt the photo to make the horizon line horizontal that isn't the case. If the intent is to make his shoulders higher I think a softer horizon line would be the better effect. That hard line makes it obvious the photo is tilted and that tilting in itself is uncomfortable to the viewer. His right hind foot is also out of position.
When you set a dog's legs in a stack, it is important to grasp them ABOVE the elbows and hocks for a more natural appearance. Ideally you would use other methods to move the legs without touching them, perhaps with some artful luring.
With the second photo, again the strongly tilted horizon line is disorienting. His front legs are not even. His hind legs aren't even either, but the front legs not being even really breaks the lines.
On both photos, I'd try to have someone out of camera shot luring to get his expression a little more alert. On the side view, I'd like to see the ears looking more forward like they are in the front view, but even.
As even and symmetrical as you can make it, this will add harmony to the over all look. We don't know what judge is going to look at these photos. I've seen judges qualified to judge GSDs who wouldn't know a correct-to-the-standard dog if it bit them. But all judges will recognize a well presented dog. Geez. We even had one apprentice judge in a match place a GSD with a dropped ear. (A dropped ear is a disqualifying fault.) In a real show, I saw a judge place a dog missing both ear tips from a dog fight.
Like I said, I can't tell you how to pose him to emphasize his most boxery characteristics because I don't know the breed well enough, but I can offer some tips on stacking on photographing that will make it look more professional and with some judges that's all it would take.
This resource, from a judge's perspective, may be helpful. I think you would want to increase the height of his front end from those photos, but I'd do it by moving the hind legs back about 2 inches and tilting slightly, but doing it with no horizon line in the background. I'd move the right hind leg more laterally to make a false horizon line on the ground that raises the front end. I'd get his head looking straight ahead and definitely alert. He doesn't have the cropped ears, so you've got to do something to get that alert expression. According to the photo, his tail should be raised.
Experiment with taking the photo slightly from above and slightly from behind rather than straight on. You'll have to find a balance to do it just a little but not enough to be obvious. I think his back is a bit long for the depth of his chest so shooting slightly from behind might shorten his back and shooting slightly from above may thicken his torso a bit.
Here's the illustrated standard I used for comparison:
http://americanboxerclub.org/illstand14.html(Remember, I don't actually know boxers, so someone who does would give better advice on positioning him.)
