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The first pitch every young player learns to throw when learning how to pitch is the fastball. At that age, a fastball is just a fastball.
But as they gain more experience, they start to realize that there are different variations of the fastball. The two most common variations are the 4 seam and the 2 seam fastball.
The main difference between a 4 seam and a 2 seam fastball is that a 4 seam is usually thrown harder and straighter compared to a 2 seam which is usually not as hard but moves more.
Both pitches can be equally effective in getting hitters out, but it is important to know the difference between the two in order to maximize their effectiveness.
What is a 4 Seam Fastball?
Most baseball players were taught at an early age how to throw a 4 seam fastball.
A 4 seam fastball is held with the index and middle finger laying across the horseshoe on the ball with the thumb underneath. The goal when throwing a 4 seam fastball is to throw it as hard and as straight as possible.
It is called a 4 seam because as the ball rotates when thrown, 4 of its seams are spinning against the air. This makes the ball more aerodynamic allowing it to cut through the air and get from point A to point B.
What is a 2 Seam Fastball?
A 2 seam fastball is typically taught to more experienced players who are looking to add to their pitching repertoire.
A 2 seam fastball is held with the index and middle finger on top of the two seams in the middle of the ball with the thumb either underneath or slightly to the side (but still on a seam) toward the index finger. The goal when throwing a 2 seam is to create arm-side movement.
It is called a 2 seam because when it is thrown, two of its seams are spinning against the air. This makes the ball less aerodynamic and causes it to move (usually to the pitcher’s arm side) based on the spin-axis of the ball.
When Should a Pitcher Throw a 4 Seam Fastball?
There are many reasons to choose a 4 seam fastball over a 2 seamer (and vice versa).
A pitcher should throw a 4-seam fastball when he wants to maximize velocity, maximize his arm slot, control the movement on his fastball, take advantage of a high spin rate, and/or throw a pitch that works off of a 12-6 curveball.
Pitchers who throw at high velocities and want to maximize that velocity should choose the 4 seam over the 2 seam because the spin of the ball will allow for higher velocities. With less movement on the pitch, the ball gets from point A to point B faster.
Yes, a fastball that is both thrown hard and has movement is ideal, but even the most successful pitchers at the highest level of baseball have to choose one or the other.
Every pitcher has his natural arm slot. For pitchers with an over-top arm slot, a 4 seam fastball might be the best choice because it allows for them to create more backspin on the ball.
Also, pitchers who are struggling to throw strikes should opt for a 4 seam grip because it allows them to control the movement of the ball better than a 2 seamer.
Sometimes, even pitchers who normally throw a 2 seam fastball go back to the 4 seam grip when they are struggling to find the zone.
Furthermore, pitchers with high spin rates on their fastballs should throw 4 seam fastballs because it allows for them to maximize the spin rate. Simply put, spin rate is the number of times the ball spins as it travels through the air. The more spin, the higher the spin rate.
When a pitch is thrown with a high spin rate and has straight backspin (like a 4 seam) it gives the hitter the illusion that the ball is rising. At release, the hitter may see a fastball coming in belt high, but when it reaches the plate, they realize it is actually up around his chest.
This creates a lot of swings and misses as hitters often swing underneath 4 seamers with high spin rates.
Lastly, pitchers with good 12-6 curveballs typically have success with 4 seam fastballs.
Remember that rising effect we talked about with the 4 seamer? Well, that plays well off the curveball that has 12-6 movement because, from the hitter’s perspective, one of those pitches moves downward where the other moves up.
When Should a Pitcher Throw a 2 Seam Fastball?
While there are many good arguments for a 4 seam fastball, there are also several reasons a pitcher should throw a 2 seam fastball instead.
A pitcher should throw a 2 seam fastball when he wants to generate more movement, is struggling to get hitters out with his fastball, maximize his arm slot, take advantage of a low spin rate, and/or work off of a sweeping slider or a fading changeup.
As stated earlier, 2 seam fastballs typically move to the pitcher’s arm side. Movement is great for pitchers – as long as they can control it. If a pitcher wants to generate more movement on his fastball, then a 2 seam is the way to go.
For pitchers who don’t have issues throwing strikes but seem to give up a lot of hard-hit balls, a 2 seam may be the best option. Throwing a pitch with more movement creates more deception for the hitter.
Oftentimes, the desired result of a 2 seam fastball is to “miss the barrel”. The arm-side movement of the pitch creates just enough deception to the hitter that the ball ends up in a different place than he originally thought after starting his swing, therefore missing the barrel of the bat.
Also, a 2 seam may be the fastball of choice for pitchers with low and ¾ arm slots. 4 seams require pitchers to get on top of the ball to maximize the spin. It is really hard for pitchers with lower arm slots to get on top of the baseball to create that backspin.
When throwing a 2 seam, backspin is not necessary. In fact, it is sometimes discouraged. Creating a little more side spin on the ball allows it to generate a little more movement.
Some pitchers naturally have a lower spin rate on their fastball. While it may be discouraging at first for pitchers to hear that they have a low spin rate, they should understand that throwing a 2 seam can actually work to their advantage.
While a high spin rate can create a rising effect on the pitch, a low spin rate can create sink. When throwing a 2 seam, pitchers can take advantage of that and generate even more sink on their fastball.
This causes hitters to hit a lot of ground balls and swing and miss over top of the pitch.
Because of the arm-side movement of the 2 seam fastball, it works great when it is paired with a sweeping slider or a fading changeup.
Sliders move to the pitcher’s glove side. This requires the hitter to be prepared for two pitches that look the same out of the pitcher’s hand but move in opposite directions.
Pitchers who throw changeups that fade to their arm-side also see a lot of success when pairing them with fastballs that also run arm-side because the pitches move the same, but the change of speed often fools the hitter.
Should a young pitcher learn a 4 seam or 2 seam fastball first?
It is best to teach a young pitcher to throw a 4 seam fastball before teaching him to throw a 2 seam fastball. It is more important for young pitchers to learn how to control a pitch than to learn how to make it move when first learning how to pitch. Once he masters the 4 seam, he can start to play around with the 2 seam grip.
Should players on defense use a 4 seam or 2 seam grip?
When throwing a ball across the infield or in from the outfield, players should always try to throw a 4 seam grip. The goal when throwing the ball on defense is to get the ball from point A to point B as fast and accurately as possible. A 4 seam grip is faster and straighter making it easier for teammates to catch.
When should a pitcher start learning how to throw a 2 seam?
There is no uniform timeline on when to teach a pitcher a 2 seam grip; however, when a pitcher seems to have no issues throwing a 4 seam, it might be time to try and teach him a 2 seam. Young pitchers with naturally lower arm slots may also be more apt to learn how to throw a 2 seam at a young age because it works better with the way they throw the ball.