Infield Footwork

If you look at the "Popular Posts" section on the right side of the page, you'll notice that one of the most widely read posts is called Shortstop Mistakes / Footwork (Part 2).  That post deals primarily with the footwork of a shortstop after they catch a ground ball.  Part 1 dealt with the steps prior to fielding the ball.  In this post, I want to add something else because if you watch many major league infielders (this includes shortstops and especially second basemen and third basemen), you may not see the "cross over step" I recommended in Part 2.  I wanted to explain why that is the case.
Obviously, the overwhelming amount of infielders who play baseball are not on the major league level.  This is usually because they come up short in one or more of the following areas:  quick hands, quick feet, and/or arm strength.  Because major league infielders are probably going to be high (or at least higher) in each of these areas, they can get away with certain techniques and mechanics that lessor players cannot.  
Footwork is a good example.  If a player is short on arm strength, he'll have to make up for it by shortening the distance of his throw and/or generating a little more momentum before he throws.  As a result, his footwork may need to be slightly different then a major leaguer's because their abilities are different.  A cross-over step after catching the ground ball will enable the less gifted player to shorten the distance and generate a bit more momentum towards first base before the throw.  A major leaguer would normally not need to do this.  This is why many infielders at the major league level apply the "shuffle step" or "replace and step" method following the catch.  

"Replace and step" : The right foot replaces the left
foot and the left foot steps to throw.

The "replace and step" footwork involves a little hop and turn where the infielder takes his right foot and puts it where the left foot was and steps with his left foot to throw.  If a shortstop has quick enough hands and a good enough arm, he can throw quite well after fielding with this footwork because he completes the process a little faster.  The little less momentum created and slightly longer distance of his throw are more than made up by his quickness and arm strength.   
Many young shortstops who try this "replace and step" or "shuffle step" footwork find that they have to add an additional hop before they throw to generate more momentum, close the distance of the throw, and allow their arm enough time to get to the release point on their throw.  Of course, this adds time to the process.  This is why I recommend the cross-over step on normal ground balls for shortstops.  It adds what many younger players need without having to take too many steps or hops after they catch the ball.  However, even though their hands, feet, and arm may come up a little short, many young second basemen can apply this "shuffle step" footwork without a problem because their throws to first are shorter.  Third basemen as well because the ball generally gets to them a little quicker and they also have a little shorter throw than a shortstop.
As players get older, the fine tuning for each position becomes more important, especially when it comes to footwork.  Every players' ability is slightly different so their footwork may need to be tailored to fit their individual needs and that of their position.