How did Paul's visual impairment help him adjust to the tough students at Tangerine Middle School?

There are two possible answers to your question.

Erik, Paul’s despicable older brother, is responsible for Paul’s visual impairment. Because Erik suspected that Paul told Mr. and Mrs. Fisher about one of Erik’s minor misdeeds, Erik and his sidekick spray-painted Paul’s eyes. Paul compares the Tangerine Middle School tough kids, who burn off steam by karate chopping each other and making inappropriate jokes,  to Erik, who unleashes his cruelty and sadism on Paul whenever their parents aren’t looking. Even though an adult  would likely disapprove of the Tangerine Middle School kids’ hijinks, Paul knows that the Tangerine kids aren’t true bullies like Erik. They are loud, exuberant, and full of life; however, unlike Erik’s profound cruelty , their mean behavior is only a show.

Paul’s satisfaction with Tangerine Middle School relates to one of Tangerine’s themes. Throughout the novel, characters learn that danger often lurks beneath a perfect surface. Things aren’t as they seem! Therefore, the Tangerine Middle tough guys eventually help Paul overcome his fears and face his brother. In contrast, Erik and Arthur, the ostensibly perfect football players, hide several dirty secrets.

Additionally, Paul’s visual impairment makes him more flexible and accepting. He says that his blindness makes him constantly feel like an outsider. He certainly feels excluded  at Lake Windsor Downs, where he is given an IEP and forced off the soccer team. Since Paul is often excluded from his community, he has a soft spot for outsiders. For example, you can see Paul’s love for outsiders in the freak show scene. Paul instantly connects with the characters behind the glass. Likewise, Paul connects to the Tangerine Middle School students since they are stereotyped and shunned by the wealthy families in the area.