Po'uha may be the bigger name (and obviously the bigger body), but Smith's absence may be the more notable one for the Jets.
The Jets have one of the deepest defensive lines in the league. Po'uha's absence, while it may not be ideal, won't have a huge impact on the game. They will likely ask defensive tackles Kenrick Ellis and Mike Devito to assume bigger roles with Po'uha out, but those two would have likely been a part of the defensive game plan either way.
The Jets gave up an average of less than three yards per carry this preseason, ranking second-best in the NFL. That was all without Po'uha, who missed a lot of the preseason as a result of his injury.
At safety, LaRon Landry and Yeremiah Bell were positioned to be the starters. The problem there, though, is that the Jets only have four safeties on the roster at present. Losing Smith brings that number to three, and leaves no true strong safety as a back-up in the event Bell gets injured.
In the event that actually happens, the Jets would likely slide Landry over to the strong side and would send in Josh Bush to man the free safety spot.
One more troubling aspect about Smith's absence: Without him, the Jets don't have a single safety from the 2011 roster available on Week 1.
The Jets' pass defense has looked impressive this preseason, giving up just under 262 yards per game to rank fifth in the NFL. They also gave up a respectable 6.5 yards per attempt, which ranked tied for 15th.
But if the Bills were wise, they'd at least test the waters on the positions where the Jets have lost talent. Po'uha is a well-noted two-gapping interior presence, and although Ellis (and the line as a whole) looked good in run defense in the preseason, the Bills could try to run up the middle. With the aforementioned depth of the defensive line in mind, they may not necessarily be more successful in that regard.
Can the Jets still beat the Bills on Sunday without Po'uha and Smith?
The Bills aren't likely to get many more opportunities to test the Jets defense deep than they were with Smith in the lineup, but with Bush possibly manning a bigger role, perhaps they could target him in the passing game.
It's a bit wild and egregious to suggest that the Jets are doomed without Po'uha and Smith, but they're certainly not better off. Barring further injury at either position, though, they should be alright.
Erik Frenz is the AFC East lead blogger for Bleacher Report. Be sure to follow Erik on Twitter and "like" the AFC East blog on Facebook to keep up with all the updates. Unless specified otherwise, all quotes are obtained firsthand.