Some very nice photos and impressive for a smartphone. Reinforces the point that the most important aspect is the photographer, the cameras and lenses are merely tools to get the job done.
Saying that, it makes sense to use the best tools for the job and the best tools one can afford because a) it maximizes the image quality and b) maximizes the chances of getting the shot in the first place.
WRT to the linked photos, they are heavily processed which really brings them out. This is something that is rarely done by typical sports PJ who are more likely to shoot straight jpgs and send them to the editor ASAP. Typically sports shots are not heavily processed images in general, and keep a more life like balance of contrast, colour tones, saturation.
There are very few action photos, the few there are are very soft or blurred, and not always in a pleasant way.
Even at such small sizes and after processing noise is apparent.
Many of them are outdoors with good lighting where most cameras will do fine- the real struggle is indoors events like basketball. Many of the photos of the indoor events are relatively poor, noisy, soft, blurred - sometimes the motion blur is very nice, sometimes it is just not working.
The images are tiny and will never make a double magazine spread or even front cover.
He is definitely at the right place at the right time which helps, and of course has a great eye to pick out nice compositions, colours, moment and events.
What is his keeper rate for high action indoor sports - something tells me it will be an order of magnitude or more worse than a Nikon D4/Canon 1DX.
Some other interesting things is that the DoF of the Iphone is massive so often times focusing is not an issue at all. Since you can't really do continuous photos you have to wait for the moment and anticipate what will happen next, this is a big thing people ignore when doing comparisons of cameras and looking at their raw FPS. Most pros would prefer 4FPS and rock solid reliable and dependable AF versus 12FPS and unreliable AF.
I know plenty of wildlife pros that Carry a Nikon D3 + 600mm f/4.0 on a big Wembly setup, but carry a Nikon D7000 (or older D90) with a Nikon 70-300VR as a backup camera, or simply when they get tired of the big gear. The smaller crop camera and lens is very quick to swing at a passing bird, less total subject magnification (450mm vs 600mm (often with 1.4 TC = 840mm) makes for easier framing and tracking (looking for a moving bird through a 600mm plus lens is very hard), the pixel density helps provide sufficient pixels per feather, the larger DOF reduces AF concerns, the slower shoot rates make you think more and be patient with the trigger finger.
I speak to a guy at Yellowstone trying to photograph a distant grizzly who just made an Elk kill, it was too far away to be much use so we chatted a lot. He said he could get a higher hit rate with his D90 and 70-300, which he purchased as a kind of spotting scope to align his 600mm + 2.0xTC because it was so easy and quick to use, he would never miss the action. When ever he sees a chance encounter with wildlife he will grab the D90+70-300 from his truck and grab the images. Of course, the big setup would provide much better images and could track far better, but that is only once it was all setup and in place. In these scenarios you are often trying to photograph one thing like a bear/wolf when a beaver/otter/coyote walks right behind you, the big lenses just are too slow to reposition sometimes. And then as Galen Rowell would say, if you can't carry your camera somewhere (and in hist case 14,000ft up wild mountain peaks) then it is useless- he preferred smaller bodies and smaller slower lenses that he could trek in the Sierra Nevada wilderness for days with, climb up towering rock walls (he was an excellent rock climber) to get the perfect perspective in time for the rising sun (yes, he often did hard climb by torch light to ensure achieving the magic hour of sunrise).
Too many amateur photographers seem to think equipment upgrades is their path to greatness, that some how FF or L glass will give them magic powers, extensive processing is a requirement and photoshop can make up for bad composition or bad lighting. Really, a good book would be a far better investment. (or course there are others that don't understand the intricacies and complexities of a modern digital cameras and proclaim that such technical understand is irrelevant to their artistic kills, which is fien except the wont be maximising their potential if they done understand the fundamentals of signal processing and optics, etc.)