The intention here is to produce a lower carb beer. This is done by using an infusion mash that starts at 65C and falls to 55C resulting in most of the sugars being fermentable (thus reducing the sugar in the final beer). This comes at the cost of body, mouthfeel and head retention. The oats and the barley are there to counteract this. Also, the IBU is low because the end beer will have a low level of sweetness, holding back on the hops helps balance out the BG:GU.