Okay, let's start with one super obvious example of a map that breaks the algorithm:
Kanzen Kankaku DreamerBoth the Oni and Muzukashii are *ridiculously* overrated. I can't even begin to describe how stupidly high the pp yield on this is.
Let me illustrate:
kevin3333g (best accuracy player ever): #1 performance KKD Oni; #2 performance KKD Muzukashii
asgardv (top tier player): #1 performance KKD Oni; #2 performance KKD Muzukashii
TKSalt (top tier player): #1 performance KKD Oni (this is a 4x100 nomod score btw, wtf?!)
The list goes on and on and on. Just finishing this pretty much guarantees it will be your #1 top performance.
Just for reference, I got my HR SS on that map literally first try, so it's not a hard map by any means - just long, but not even *that* long by accuracy players' standards.
Now for the other maps in my top performance list:
AugoEidEs - This was a good score back when I got it 8 months ago, but nowadays it's really not that impressive anymore. The patterns are simple and repetitive, my accuracy is subpar compared to pretty much everything I consider my true top scores. The BPM honestly isn't even that high by taiko standards (207 BPM), so the only real difficulty here are length and SV.
rog-unlimitation - This is actually a good score, nice job algorithm. Doesn't really deserve to be all the way up at #3, but I certainly won't complain if this stays in my top 10.
Rengetsu Ouka - Uh, why exactly is this here? I got it literally first try, not that hard. I mean, it's not a bad score or anything, but the BPM is not high enough to make it actually difficult. My accuracy isn't too hot either.
Mythologia's End - Wat. This score isn't impressive at all. Mediocre accuracy, I even got misses. Even 8 months ago when I got this score, I wan't pleased with it. Only difficulty is map length.
Son of Sun (Extended Mix) - Well... I personally don't really like this score, but I can see why your algorithm would consider it a good one. I can accept this one (reluctantly).
Power of Dream (Night Fever Refix) - Shitty accuracy, but at least the map is kinda tricky. Same as for Son of Sun; I don't really agree, but I can accept it.
Magia (TV Size) - Accuracy is literally the only difficulty here, and I have like 50 scores that I'd consider better accuracy performances.
Seikan Hikou - Another score I got on my very first try. I ragequit after getting it because my accuracy (only real difficulty on this map) was so terrible, so it kinda hurts my feelings seeing it in my top performance list haha
Rainbow Dash Likes Girls (Stay Gay Pony Girl) - Honestly not all that hard, and I missed on it. Really outdated score as well. Oh well, at least it's harder than most maps on this list, so I'll take it.
The feeling I get is that high BPM is overrated in a weird way. Playing anything below 200 BPM doesn't seem to be worth much (unless it has 1/6 streams and OD9.8 like Power of Dream). Yes, high BPM is generally harder, but 220~ isn't as difficult in taiko as it is in standard. I have no issue with weighing 270 or 300 BPM scores really highly, but right now the scales seem to be tipped way too far in favor of 200-220 BPM maps. A better way to put it might be "lower BPM is underrated".
That being said, I don't fully understand the speed weight either - my FC on
Forgotten for example is a lot more difficult in terms of speed than anything from my current top performance list. While I agree that it's not an outstanding score due to mediocre accuracy and repetitive/simple patterns, it's still harder than 90% of what the algorithm considers my top plays (the 10% being rog-unlimitation).
My accuracy plays don't seem to get any love. Stuff like
Endless Tears...,
Manima ni,
Munchy Monk Circus,
Anison Sprint (Anime Song Medley) and others are (in my opinion) a lot more impressive performances that all of those mediocre 200-ish BPM scores.