Both of these pitches can put unnecessary stress on the upper arm and I rarely coach this pitch with anyone under the age of eighteen. And even then, with conditions that totally support a healthy environment like perfect mound conditions and always with a player with good nutrition and training habits. However, most “kids” high school age and below are a hit’n-miss with these disciplines not to mention their various stages of growth and physical development issues.
However, to answer your question
The forkball can be best described as a pitch in the breaking ball family –but with a “look-see” given to the batter as a knuckler …with a signature at the last moment, of literally dropping off the table—and I do mean dropping. Usually, the ball will drop down with the batter swinging over the top. This pitch can be very effective against a power hitter when the proceeding pitch was a fastball on the outside and called a ball. Why? Because there’s a high probability that the batter will think that the pitcher is now trying to correct the last call – ball, for a strike, and he (pitcher) just dished up a creampuff. So, the batter usually has a “so long Mr. Rawlings”, look on his face --- just before he swings like a gate and lands on his pockets. (gotta-love it!). The grip can vary from pitcher to pitcher. Depending on the pitchers physical endowments of hand size, muscle coordination, and most importantly the pitcher’s practice disciplines. Practicing this pitch – oh…three or four times a week, will - I guaranty you, will have looking into the lights. A pitch like this to be truly effective must be at the end of a long and rigorous training session specifically designed to handle this and other pitches like the knuckleball, curveball, and slider. (note – the slider is in the fastball family of pitches) A common problem with youngster that have early success with this pitch is the reliance on using it at the wrong time. Also, because this pitch has to “drop” at a location in front of the plate, a batter that cheats up in the box ever so slowly can rip this pitch right back at you when you least expect it. Also, if your forkball goes to “deep” into the plate and lands in the dirt in front of your catcher, there is a high probability of a pass ball. Also, with high school play and below, it’s not advisable to use this pitch with runners on. The probability of a hit into the “gap” is very high. The release point with this pitch contributes greatly to the stress on the arm – since it’s released like a fastball but has more push to it , because of the grip. Most pitchers - even in college ball, tend to over pitch this deliver by throwing the ball - not pitching it. Hence, the release tends to be straight out in front instead of slightly higher – about hat level. Again, this varies from pitcher to pitcher due to the particulars that I mentioned above.
The Splitfinger Fastball, as the name implies is a pitch in the fastball family of pitches. And as such has a grip and release similar to the two seam fastball. But what’s really the earmark of a great splitfinger is the ball’s signature about five(5) to fifteen (15) feet in front of the plate. A splitfinger fastball can actually appear to “speedup” as it reaches home plate and then move a bit – down/left/right In fact, a great splitfinger can – when practiced rigorously and with propr coaching/supervision, can be a mainstay. A true gift for any pitcher that really has hopes of going pro. The splitfinger has the look of many different pitches that some batter’s key up on, yet, it can paint the plate when you need it the most, it can also “jam” a batter just when they dig-in and think they got-cha, and on and on. The grip and arm slot, combined with the pitchers upper torso progression forward are the main ingredients here. To give you a point-by-point descriptive narration would not do you justice. You really require a pitching coach that brings a ton of experience to the table to truly give you the what-for-ever on this pitch. However, with learning this pitch – and I’m telling you this from experience, you’ll have great success in the beginning thinking that you’ve got it. But that success doesn’t last long because you won’t change the pitch’s signature. Remember, a splitfinger fastball has to be great – not just good. So, most every batter you face should be chasing this pitch, not just swinging and missing. A fine point – you say? Yea, but there in is the beauty of the pitch – you not only get strikes, but your sending that last batter back to his bench say --- “what the heck was that?” The rest of his crew is walking to the plate thinking –“what on earth is this guy doing up there?” Your also messing with the mind of the third base coach. Like I said ----“gotta-love it”.