This is the first year in band that I have felt that I am in a crapy band. We just played a concert and the performance was terrible. My high school concert band has never played this bad! Last year we played "English Folk song Suite", "Fortress", and "Army of the Nile" which are all harder than the pieces we played this year yet we still did terrible. Anybody have any ideas of why this happenned.

are you really asking us to speculate on why your band sucks without ever hearing them play? or was it a rhetorical question meant more to vent frustration?
there are many reasons why an ensemble can sound bad
bad intonation, bad tone, bad time...
generally comes from people not practicing their parts, people not listening to each other when they play, and not taking a submissive role to the lead/principal players.
everyone always seems to think it's everybody else's problem..
he's out of tune, timing's off, horrible tone
if more people took more accountability, i really think it would help a lot.
what sir, do YOU do to work on intonation? work with playalongs, drone tracks, recordings?
what do YOU do to work on time? do you practice with a metronome?
what about YOUR sound? how much real focused practice do YOU do everyday that focuses just on your sound? how does your sound blend with the section?
my point is, you are complaining about everybody else... and it sounds like you are saying you're playing right and everybody else is wrong.. how can you be so sure you're not just as much part of the problem?
maybe songs like Army of the Nile are harder for you.. maybe they're easier for others. what challenges others may not challenge you. i've played all those tunes you mentioned... let me tell you.. compared to what's out there.. they're not that hard.
if you're truly the prime musical example, that's all you can do .set the bar, and hope others follow. if you're not, get back in the practice room and quit complaining about everybody else.

I know how to fix it. Do you have a baseball bat? fine out where each kid lives and then break in to there house late at night with a ski mask on bring your bat and.......... You can figure the rest out.
Seriously I was in a group in eroupe that had a couple of players that were really bring the group down we all lived in a dorm and one night...bar Soap wraped in a blanket........Would have worked but we just had a couple section leaders talk with them, and they asked the guys if they liked playing there horns of course they all said yes so we asked them if they would play there horns a little more, when they were by them selves. (never mentioned the word practice) that made it all better.