Ok, the guy is not some Fields medalist, so it depends what you mean by math chops, but here are a few of his papers published in respectable journals that have

Ok, the guy is not some Fields medalist, so it depends what you mean by math chops, but here are a few of his papers published in respectable journals that have non negligible math content: https://www.sciencedirect.com/science/article/abs/pii/S0378437118301894 https://www.sciencedirect.com/science/article/abs/pii/S03784... (free at https://arxiv.org/pdf/1707.01370.pdf https://arxiv.org/pdf/1707.01370.pdf) https://www.sciencedirect.com/science/article/abs/pii/S0378437110002189 https://www.sciencedirect.com/science/article/abs/pii/S03784... https://www.sciencedirect.com/science/article/abs/pii/S0378437115001429 https://www.sciencedirect.com/science/article/abs/pii/S03784... (free at https://arxiv.org/pdf/1405.1791.pdf https://arxiv.org/pdf/1405.1791.pdf) https://www.sciencedirect.com/science/article/abs/pii/S0378437116000923 https://www.sciencedirect.com/science/article/abs/pii/S03784... (free at https://arxiv.org/pdf/1505.04722.pdf https://arxiv.org/pdf/1505.04722.pdf) https://www.nature.com/articles/s41567-020-0921-x https://www.nature.com/articles/s41567-020-0921-x There are plenty more btw, these were the ones that I could find in more prestigious journals. if you follow him on Twitter you'll see that he also does quite a bit of recreational maths too.