Last year the Seahawks went 0-4 in preseason and finished 11-5 with a wildcard berth in the regular season.
The Raiders and Cardinals were each 3-1 in preseason but finished 4-12 and 3-13 respectively.

Every year there's examples like this: teams that look like crap in preseason but do well in the regular season, and teams that look great in preseason but can't cut it in regular season, which is another reason I don't put stock into preseason results as any kind of determinant for team success in the regular season.

Football is a team sport which depends on players chemistry and that's hard to develop when a significant portion of the players are just passing through (though sometimes things fall into place quickly or temporarily based on momentum). The main purpose of these contests is just to grade individual performances, not the team's, so they can narrow the roster down.