The 49ers host the Seattle Seahawks this weekend knowing that a win will go a long way to securing a post-season spot.
Willis told NFL.com: "I think we're better than our 8-4 record suggests. We've been through some adversity but we've done well as a team in my opinion.
"Every year teams are labelled favourites but history shows a bottom seeded wildcard team are hungrier and go on and win it. We've taken on a bit of an underdog mentality and we've got to play like we have something to prove.
"We're a good football team. We're ready to go and I'm looking forward to playing the Seattle Seahawks this weekend."
When the 49ers and the Seahawks met back in week two, Seattle dominated their rivals to end up resounding winners.