Has anyone noticed the types of pitches having any effect on pitcher performance? Or are they just window dressing? Anecdotally it seems like guys with similar ratings tend to perform worse if they don’t have a fastball, but it could also be completely in my head.

It means nothing.

The pitch names are almost as dumb as the "Asian" player names.

I remember them saying a while ago that they design the players ratings first and then design the pitches based off of that.

So if you have a pitcher with high velocity they might have a fastball as their first pitch.
If they have a high groundball to flyball rating they may have a sinker as their first or second pitch.
If their velocity is low with a low GB/FB the first pitch might be a knuckleball.

But from what I remember the ratings are programmed first, then the pitch type is to 'dress it up' rather then the other way around.

That’s what I figured, thanks all.