Answer: Your question is a bit of a misnomer in itself and your coworker doesn't seem to understand thermodynamics - The real question is why the center of the oven is warmer than the outsides of the oven, which yes, is partially due to convection (the movement of the fluid in the oven circulating away heat as it travels) and the design of the oven (where latent 'pools' of fluid allow heat to build up), but is mostly due to the fact that the fluid being circulated is AIR which is an insulator due to the nature of the gas composition and it being in gaseous form. Air insulates regardless of its velocity, but as father Bernoulli taught us, the faster it moves under constant pressure, the less entropy is able to pool into measurable heat. For this oven, it makes sense that the outsides would be cooler than the insides, since the whole point of an oven is to concentrate high heat within a container that won't combust. There are other issues at play such as the difference conductivity and radiation constants of different elements, but that's another reason why oven's are constructed with materials that melt far above the safety limits, such as sand/acrylics. You can measure this yourself by going into a temperature controlled environment (read: "in-doors") and touch a wooden surface, then touch a metal surface, noting that the metal surface will always seem cooler to the touch because metal is a poor insulator and will emit heat calories to entropy at a much greater rate than wood, which is carbon-based and has evolved to literally be pockets of air at the molecular level.