What is your definition of brutal? There is no such thing as a "shutdown corner" in today's NFL. QBs and receivers will always get some yards, points, whatever. I look at Eli's stat line, take away that ridiculous Jennings TD and the guy threw for 161 yards and 2 TDs. That's not spectacular. I saw Gilmore playing tight coverage, keeping almost everything in front of him, and tackle very well. He allowed two of six targets to OBJ for eight yards, and all told allowed 49 yards and one TD, plus one INT.
If you mean he was picked on in that balls were thrown in his direction, well that's nothing new. Through the first three games Darby and Gilmore were the #1 and #3 most targeted corners in the NFL and they have both performed admirably.