What are the flaws in the book The Crucible? (not character flaws but those mentioned in Miller's introduction of the book)
In Miller's introduction, he flat out tells his readers that his play should not be used as a history textbook on the events of the Salem witchcraft trials.
This play is not history in the sense in which the word is used by the academic historian. Dramatic purposes have sometimes required many characters to be fused into one.
Miller freely admits that he took liberties with character's ages. For example, he made Abigail older than she really was. Miller also admits to reducing the number of judges that were present for the trials. That's important to note, because the play makes it seem like two judges were responsible for the tragedy. History is much worse, because knowing that a bunch of judges are to blame makes it way worse.
Miller also admits that the personalities of each person in the play are his creation.
They may therefore be taken as creations of my own
That means the sympathy that the reader feels for John Proctor might be wrongly placed. He might have been a jerk in real life.
What is important about Miller's play is that the people involved in the witchcraft trials are real people. What is also true is the outcome. Miller didn't kill any characters that were not actually accused, sentenced, and executed in the actual American history. To that end, his play does a wonderful job at making the events of a horrible time in history come to life.