How is Mr.Tates testimony significant to the overall trial?

Heck states that he received a call from Mr. Ewell claiming a black man raped his daughter. He adds that neither one of them had ever called a doctor. Heck says that Bob Ewell was with his daughter when he arrived at their place. Bob declared that Tom had raped his Mayella. Heck describes her injuries, "She was pretty well beat up, but I heaved her to her feet and she washed her in a bucket in the corner and said she was all right." Heck's description of Mayella's injuries are consistent with Atticus's interpretation of the attack. I think however, to the biased white men on the jury, they might only have seen Bob Ewell's story in what Tate described.