Alex Gonzalez awaits a throw exactly where it
should be on a pick-off at second base.
Whenever a pitcher spins and throws to second base, he should aim for a spot that is just to the third base side of second base and about thigh high. This accomplishes a couple things that make it easier for the fielder to catch and apply the tag to get the out. A throw that is just to the third base side of second base takes into account that the runner is coming in from that direction. If the throw was directly over the bag, the fielder would have to catch the ball and then take the ball to the third base side to make the tag. If the throw is already on that side, the fielder just has to catch the ball and lower the glove to the runner. This is usually a little quicker.
A throw that is thigh high takes into account that the runner probably will be sliding. If the throw is lower, the ball has a good chance of hitting the sliding runner and possibly ricocheting into the outfield. If the throw is too high, it will take longer for the fielder to catch the ball and bring it all the way down to the runner. Throwing it thigh high allows the ball to be a little higher than a sliding runner but not too high where it's tough to get the out.
The combination of a third base side throw that is thigh high puts the defense in the most effective position to get the out on the pick-off at second base.