Better 800 meter shape=feel more spent after a race?

I've experienced the same thing. I think it's linked to the fact that 800 training requires you to go hard often in training. It teaches you to go to the well basically. I listened to a podcast where Vebjørn Rodal(1996 OG Champ) talked about the same thing, that as soon as he stopped training as hard, he lost the mental as well as physical ability to push himself very hard in training. He said he became "careful" in training and lost some of the edge.

Congratulations, you've discovered the Central Governor Theorem.

Except the distinction between mid-distance and distance training doesn't exist. The same thing happens with marathoners. When you're in shape and tapered, you can dig yourself into a deep hole, far deeper than if you just decided to grind out a 26.2 mile long run at the end of a regular week.

I know exactly what your talking about but I’m pretty sure it due to what kind of shape your in and what training you’ve been doing. If a distance based guy runs an 800 his limiting factor will be his speed and will completely max out the ability of his leg muscles but will have some reserve aerobically. A 400/800 guy who runs the same time as the distance guy will have some speed left in reserve but his lungs and aerobic system, (therefore his entire body really) will be maxed out and will be pushed way beyond its limits, and he will feel like garbage and will take longer to recover after the race. I’m just speculating about the reasoning behind this but I’ve experienced running similar 800 times when I’m aerobically fit versus really really fast and the latter made me seriously worry about the safety of my own lungs, I legit thought I was dying and needed 5+ minutes before I could do anything. So to summarize maxing out your aerobic system is more painful than maxing out your leg speed.

When I mentioned the distinction between distance and mid-distance I didn't mean that a distance runner doesn't have the same thing, for distance races. I believe it just works specifically and not generally. I believe marathon training probably would enable a racer to dig deeper, but for a marathon. In marathon shape in an 800, not so much. I think the internal controls, the "central governor" if you will learns a program from the training and perhaps also the racing itself. It's not that a distance runner is not tough or gritty, I just think the longer training might confuse the system because a different scheme of energy expenditure is ingrained.