Pride is an evil companion. Gibbs knew that well enough. However, not even he could fight it. His pride in his team, his friends, his family always led him down into dangerous territory. Always trying to keep his professional distance, but these men and women always got to him and he was proud of their dedication.
It was when that pride came to back to bite him in the ass with a vengeance. Suspects, and the confirmed guilty, had a sense of his emotional link to his team and knew that it was that pride that would be his downfall.
Abby's stalker, Tony's many accusations of murder, Ziva being framed for terrorist acts, and McGee's protection of his sister during her investigation. Boone was keenly aware of this weakness and used it. Lucky for Gibbs, he failed and got the chair. One bad guy down and now the question was how many more will there be?