We need to improve on offense and defense. DE is a bigger need because that is the one thing the defense needs to be very productive. Ideally we would like another upgrade at LB or another upgrade at DT. But DE is the only glaring weakness on the defense right now. It would make every other player on the defense a lot better.
As in the offense, it is going to take several players to improve that. You can add 2 players to the offense and it will still go nowhere. when FA began, The offense needed another recieving threat, center, and a guard, at least. Now, we have our center. We still need a TE/WR and a guard. The offense needs help on other things as well that are questionmarks. Such as QB. We might still have an issue there. All in all, the offense is a mess and it isn't easy to fix. The defense is an easy solution.
But we need to make more turnovers on D. The D is good at stopping teams from scoring points. But they are not good at turning over. If we get turnovers, our odds for winning just went up a lot.