Well, my 2013 MBP does that, to the point that if I leave it for 6hrs it's out of battery such that I cannot even turn it on. Real shitty. Don't know if I'm just bad at this stuff or if most computers do that.
Your battery might be shot or it might not be really sleeping. Either way you can try changing it to hibernate instead of sleep using a command line utility (pmset I think). Not nearly as convenient but if your battery is dying that quickly convenience is probably secondary.
You've probably already looked but console might actually tell you exactly what the culprit is. This has happened to me in the past a couple of times. Once with an app running in the background that I can't remember the name of that wouldn't even let the screensaver start, much less sleep. The other time was because of a kernel extension shitting the bed on a regular basis. If you're curious what non-Apple kexts you have installed you can see them like so:
kextstat | grep -v com.apple
They're at /Library/Extensions/ and you can disable them like this:
Even if it's not a kext it's good to keep tabs on kernel extensions you have installed. I hope that helps and apologies if you're already aware of all that.
Keeping batteries fully charged all the time makes a HUGE difference in their lifespan and ability to hold a charge. If you regularly let a battery run down under 25% you're directly contributing to the "won't hold a charge" problem.
I can't speak as well to the bottom end, but if your hardware provides the option (ThinkPads generally do, at least with Windows), cap the charge at somewhere between 80 and 90% to maximize battery lifespan, and set it to not start charging unless it's at least 10-15% below that maximum charge level.
At the fully-charged end of things, think of the batteries like latex balloons - if you repeatedly fully inflate them they're going to have problems sooner than if you just mostly-inflate them every time.
