Jimmy mentioned this in the book as well.
It made him realize how important backup QB is in the NFL and really what prompted him to trade for Steve Beuerlein the following season. That's what I love about Jimmy. He obsessed over weaknesses and worked tirelessly to correct them. After the Lions trounced us in the playoffs, he saw a weakness in our pass defense. So he moved Kenny Gant, acquired Thomas Everett from Pittsburgh, drafted Darren Woodson, and drafted Kevin Smith. That season, we were champs.
And that's another thing I love about Jimmy. He was constantly evolving. Never looked at any player with rose colored glasses. Hell, he was the guy who had to tell Cowboys legends like Ed Too Tall, Danny White, and Randy White that it was all over.
Why the Garrett regime was always too stubborn or too ignorant to ever learn from a beat down, I'll never understand. All the great ones do.