Curveball vs Slider

  Today I feel like talking about something other than Major League Baseball, because the season is over. So today, I'm going to talk about the two most common breaking pitches, the curveball and the slider.
  As a practitioner of the curve, I know that the grip is fairly simple. You place your index and middle fingers along the vertical seam, lean towards your middle finger, and throw the ball so your middle finger is on top of the ball. Most curveball experience slight lateral movement and heavy downward movement. For people who didn't understand that, imagine the ball starts at the two on a clock. It breaks heavily, winding up somewhere between seven and eight. Other variations have different movement, some go from the one position to the eight, others go from  the two to the eight, but the most famous variation, literally called the 12-6, moves only from the twelve position to the six, with no sideways movement what so ever. There are certainly more variations of the curveball, and some could argue that is breaks more, but this is mostly because of who use which pitch. Starting pitchers mainly use the curve, and they tend to have better mechanics than relievers.
  The slider started off as the slurve, a variation of the curveball that had only a little downward action. Since then, the casual fan has found it difficult to distinguish between the two. One way to know is to see how fast it moves. Sliders are typically five miles per hour slower than a pitcher's fastball, sitting around 87 miles per hour. A curve is ten miles per hour slower. Think back to the clock. A slider will typically start at the three position and finish at around 8:30. Sliders are mainly used by relieves, as the grip (curveball grip with the fingers on the side) puts more strain on the arm (relievers throw less pitches). But those lines aren't final, as possibly the best starter in baseball, Clayton Kershaw, uses both the slider and the curve.
  When it comes down to it, which pitches you should use really depends on your mechanics. If your short arm the ball, and come around your shoulder, then you can really get sharp action on your slider. If you come straight over the top, stay long through the zone, and stay within yourself, the you should throw a curve. Your arm angle would simply move your fingers to the top and you'd throw a curve anyway. But none of that matters. The best off speed pitch, if you get it right, is the change up. It puts the least amount of strain on your arm, has an easy grip to use (circle with your index finger and your thumb) looks like a fastball, and is slower than either of the breaking pitches. If you need more proof, look at Pedro Martinez. The Hall of Famer's out pitch was a change up, and he dominated the American League during the Steroid Era, which, needless to say, is difficult. So learn either three. As long as you have a strong fastball to pitch your off speed off of, you'll do fine.