It shouldn’t affect velocity at all. The crossfire, as I have said before, is a move that works only with the sidearm delivery, and it has nothing to do with the speed. What it does have to do with is the angle from which the pitch is delivered. You’re a righthander, right? So what you do is, after you’ve gone into the windup or the stretch, take a step toward third base, whip around and deliver the pitch from that angle. If anything, you get more momentum and therefore greater speed as you do this. I’ve seen guys like Jeff Nelson and Randy Johnson, both of whom were true sidearmers, and if you watch them you’ll notice how they got the entire body into the action and therefore more power into their pitches. They both used the crossfire with devastating effect.
And don’t worry about throwing across your body—most sidearmers do this to some extent, and it actually assists in the follow-through—completing their pitches. I remember when I picked up that delivery, when I was about thirteen, and I fell so in love with it that I was using it most of the time—a fact that was not lost on my pitching coach. One day he was helping me with my circle change, and he commented “I know you’re going to crossfire it. You use that move with everything you throw.” I’ll tell you something else—few things will discombooberate the hitters more than having to face a sidearmer who uses the crossfire, because they don’t know where the pitch is coming from!
I would advise against dragging the foot, because it’ll slow you down, and you don’t really want to do that. If you want to change up on a pitch, you can do it by altering the grip, tightening it or loosening it, or holding the ball a little further forward or further back in the palm of your hand (but don’t grip the ball too tightly, because you don’t want to squeeze the juice out of it!) In any event, have fun with the crossfire—it’s a beautiful and deadly delivery, believe me. 8)