The review score is extreme because the way microtransactions are handled in this game are extreme. Different reviewers have different perspectives of the way this is handled, this reviewer puts a large overall value in the enjoyment of the career mode and other modes where VC is pushed, which progress is mind numbingly slowed to a horrible pace due to their need to push microtransactions. It's why I never bother with the mode because of how un-fun they have made it, due to the grind that you have to do to even get good and compete online.
An alternative way to handle this was IGN's coverage, where they specifically call out microtransactions as being pay to win and a huge step back:
They gave it an 8.4 out of 10. Which if you are only looking at the score and didn't read the text, you'd think there was nothing wrong with it. The difference between IGN's review, and the 6th axis' review is that the IGN review placed a premium on the on court product, whereas the 6th axis review takes a look at other modes affected by VC (the story mode, the neighborhood, pro-am, park, MyTeam) and sees the unfair nature as to which microtransactions are handled at the expense of the consumer.
Both ways of handling the review score are fine with me. The 3 out of 10 is a legitimate score because of the way they designed the game's overall pay to win structure to monetize their consumers at the expense of their time, and their enjoyment of the game.