Don't mean to hijack this thread, but I'm experiencing this very thing with my Harlequin Rasboras as well. I had 8 a week and a half ago, and have had 3 die since then. Much like the OP, they're not all at once, but spread out over a few days.
I've also checked my parameters and everything is in check. I've done 50% and 15% water changes all in one week, and yet still had a fish die this morning.
There is some red algae on my rocks and heater. And some alage on the plants, but I dont' think anything serious. Maybe pics would be beneficial.
And like the OP, I'm also a Cubs fan, so maybe it's the cures of the Billy Goat....