I've gotten back into Team Fortress 2 the last 2 weeks. Still using medic class most of the time because usually the team needs one. I don't mind because it's one class where you can see the visible effect of your efforts. A good medic can keep 3 people alive on the front lines who would be dead. Then every few minutes you can push in with an ubercharge and break a stalemate. You can't win without a good medic working with a good attacker.
In the last 3 days I have encountered some great teams and awful teams. Oh, and one inexplicable team. Bad teams are characterized by frontal assaults leading to death and not knowing when to retreat. Good teams have good communication and advance or retreat as a group, warn about approaching dangers, and correct each other's behavior.
Last night was the first inexplicable team I have played on though. Our team of 12 people had 7 engineers, 3 snipers, a demoman, and a pyro (me). 7 ENGINEERS. They only built defensively and only side our own base.We had an incredible defense built up and all 7 engineers running around building and repairing their sentry guns. They did build a teleport though...from the upstairs to the downstairs. It was actually faster to run down the stairs or jump the railing. Outside we had myself and 2 snipers, which made us the most useless forward assault team ever. I do not know how we held off the other team for half an hour inside our base. It was an incredible display of stubborn refusal to adapt. Maybe it was the 'practice makes perfect' theory: that if they positioned the sentry guns just right it would be impenetrable.
Well that theory was bogus because of one thing: spies. Yes, the spies who can sap a sentry gun and take out a whole room in 10 seconds untouched by any of those guns. This happened over and over. I cajoled, begged, and demanded the engineers switch to an attack class, but nothing happened until right at the end. Finally one switched to a Heavy and we seemed to make some progress, but it wasn't enough. Eventually the scouts and spies overwhelmed our sentry gun porcupine creation.
So we had an all-defense strategy with a major flaw: TF2 favors attack. Attackers can hide and build up ubercharges or just repeatedly storm the place and eventually win. Defenders have to be absolutely perfect forever. Well, until the other team trips up and you switch to offense and push them back. If the team never pushes out and attacks, though, you just can't win. As they say, you can't steal second with your foot on first.

All that aside, I was in total berserker mode as pyro this morning. I gave up playing medic for two reasons: my teammates were too stupid (okay, maybe inexperienced) to take advantage of ubercharges*, and spies were stabbing me in the back every 2 minutes. I played a
perfect pyro the last 3 hours. I ambushed; did hit-and-runs; disrupted offensives; nailed entire teams from behind as they massed to attack, spychecked like I had obsessive compulsive disorder; was generally a cuisinart of death. I caused confusion, chaos, fear, and uncertainty in the other team and racked up a massive death toll - everything a pyro should do. It was awesome.
The frustrating part of it was that it was only me attacking. The rest of my team was holed up in our base building sentry guns and shooting arrows out. In one rush I took down a level-2 sentry gun, 2 teleports, and 7 enemies on the bridge (Badlands map). I thought my team was behind me to finish claiming it, but I was alone on the empty bridge, surrounded by burning carcasses and sparking electronic remnants. I started to pull back to find my team and was shot by the other team respawning. My teammates hadn't even left the base.
Still, my awesomeness has left me in a great mood.
* Note to Demomen: when you are ubered please attack the sentry gun ripping us apart. Don't wander off and start putting stickybombs in the area we already control.