I understand sliding perfectly well, and when I was writing about it, it was for sliding the lever in a stick with a square gate. I wasn’t even talking about buttons other than hold them in if you are having these problems.
Sliding over buttons is probably your problem that causes you to neg edge. It’s likely you are still pressing them down after moving your thumb to another. Why would you play like that anyway? Can’t you use a lighter touch? It’s not only less stressful on your thumbs but also faster input wise to use light tapping over having the physical surface of your thumb fighting friction against the physical surface of the pad and then the edge of the buttons… In fact, I just took 10 minutes of my time to test it your slidey button way vs quick, light taps on a pad. I’m a stick player keep in mind. Quick light taps I got 24 out of 25 cMP to EX FBA combos, 1 SHC on neg edge when I accidentally pressed up too fast. My fault and I derped out a charge too fast. I tried sliding my thumb from button to button doing things the same way as the other 24 that I did perfect. About 7 out of 10 (I didn’t want to do another set of 25) ended up with SHC neg edge.
On stick I did a perfect 25 out of 25 with no neg edge SHC.
Regardless of pad or stick, this is execution error on your part anyway. Stop laying blame on the pad that it’s your limiting factor. If your method isn’t working out for you, then you either need to change the way you play because you currently aren’t as successful as you should be execution wise or suck it up and pick up a stick and have less of these issues.
If you are still getting neg edge SHC from cMP with light button taps, then you are pressing U too fast after having released the P button and not when you hit both K buttons. If you already have the up motion input between letting go of P yet before you hit KK, then obviously, you will get neg edge SHC.
^ Execution error. I sometimes do it too, but mostly in ST, rarely in SF4 mainly because of the large speed differences. Obviously, this is my fault, and usually happens when I am not paying particular attention, panicking, or rushing things instead of being calm and doing it the way it should be done.
In the end, it boils down to you. Why should the game pander to your errors?
I have 2 really bad execution errors in SF4. 1 is back to forward charge after a standing attack to RCF. I have a really difficult time doing this. My other error is pressing KKK too soon during U1 to my wall motion. 1 frame links are also not a strong point of mine, but thankfully, those have nothing to do with negative edge or motion inputs.
Just thought I’d share some of my own errors, I do not want you to think I am on a high horse. We all have execution errors. Except maybe Zeus, never seen someone so consistent at 1 frame links, lol.