Kids will probably love this but, as a parent, I found it a not particularly enjoyable read.
When the young boy in the story, Adam, is constantly belittled by both his brother and, unforgivably, his father, it makes for an uncomfortable read. The fact that they change their minds at the end seems a little bit of an afterthought, in the context of a 'fun' football story. It's like the author had the idea, then felt the need to bash the reader over the head with it on almost every page. The constant verbal abuse sent shivers down my spine, although my 6 year old probably missed any subtext, thankfully.
The message seems to be: Don't worry if you're not very good at something. Just prove people wrong and they will like you again. Is this how the father-son relationship should work?