Offline
I don't know that we are one or a few pieces away. I think we're more like one or a few plays away. The two best teams were in this last Superbowl, and arguably, the best team won it. The year before? The best two teams lost (got hosed) two weeks before the superbowl.
2018 Eagles had a deep rotation on the D-line and not much else. They were not the best team in the league that year.
2016 / 2017 It tastes bad, but honestly, the Falcons and Panthers were the best teams and neither won the superbowl.
2015 Seattle was the best team but lost a close one on a boneheaded play in the SB.
2014 Denver was the best team and got demolished in the Superbowl.
Heck, even when we won the superbowl, the Colts were thought to be the best team.
A lot is said about filling this hole or that hole, upgrading weaknesses, adding depth where we're thin, etc... All of that is true, but to win a Superbowl, a lot of things have to go your way. Like it or not, luck plays a huge role in any team's superbowl run. All you can do is put the best team you can put together on the field and play the games. Get to the playoffs and hope the funny shaped ball bounces your way and the refs don't butt in.
We have a roster that can win the SB. For much of the year, we were considered the most talented roster in the league. Key injuries hit us in week 16, we got no help from other games (and refs) in week 17, and we didn't play our best game in the wildcard. Even with all that, we were right there.
The Eagles just got hot in the playoffs, as did the Giants both times they won. Which adds some credibility to the assertion that there's no such thing as a "perennial playoff contender" that isn't in Super Bowl contention. If you make the playoffs, you have a chance.