Yes, pitch speed is one of the most important sliders when balancing for yourself, and pitch speeds are higher this year. If you were good on 5 with all-star last year, then you need to bring it down to 4.
I say user's choice not because it isn't important, but because the sliders will still apply effectively no matter the pitch speed. It is actually very important that you find the right pitch speed for you. General rule of thumb, if you find it impossible to get ahead of a fastball, you need to slow it down. If you're rarely behind a changeup, you need to speed it up.
Edit: Keep in mind these sliders are extremely tentative right now. I'm not playing these sliders right now, and I'm not going to post the news ones because I'm in a relative state of flux. Don't expect sliders that I'm actually confident in until late April.
Edit 2: Also, the ideal timing is a wee bit earlier this year based on the visual ball travel then last year. It's subtle, but at this point I'm confident it has changed.