I use this pass a lot, but I sometimes have trouble establishing side control, especially against really good guys. Last night I did this to a VERY flexible black belt, but I slid too far and my base was a little off. He just threw his legs up around my neck, threw me on my back and scissors choked me lol. I came back today to see what I was doing wrong and I figured it out. Marcelo keeps his back very erect when doing the knee slide, and it looks like this allows him to maintain control of the position while still executing the movement very quickly.

I feel like a strong opponent wont let the first part of this happen but they may not necessarily be expecting the next move.  Regardless, I love the baseball slide.  Can't wait to give it a go!