The only time I try throwing harder at spares is when I'm just so upset with what I'm doing that I just chuck it down the lane and I don't care if it even stays on my lane, this doesn't happen too often. I find throwing straight, especially if I have a plastic ball, that there is automatically more ball speed with the same swing speed. Less friction and less flare equals more ball speed.

Well since almost everyone has said this, Yes I am throwing a plastic spare ball. Just wanted to answer that. And thanks for the comments, I worked on it today and I am finally back to picking them up like normal, I actually moved to the right about three boards instead of left, and I'm getting it there perfectly.

Sometimes that works too. Its about what works for you in order to pick it up 95% of the time or better on any condition.

Today's high tech balls will hook or cross over your line if you throw a straight release. The reason behind the spare ball was to reduce a ball movement in a straight roll and improve every bowler's spare game.

To answer your question. When you throw a hook, your release is slower because you're turning your hand and wrist so there is more motion involved.

When you throw any ball in a straight manner and no wrist or hand movement involved. You have a increase swing because there is no motion involved.

So there is no need to throw harder or think you need to throw harder.

If you want to keep that mentality then you're going to hurt yourself soon.