By Alex Eisenberg
A pitcher's tempo is often an indicator of the kind of velocity a pitcher throws with. The faster a pitcher's tempo, the more momentum the pitcher carries into foot plant. A faster tempo also forces the arm to speed up with the body, which helps eliminate any stoppage or hitch in one's arm action.
Tempo is defined as "the speed in which a pitcher can go from the point to where their knee reaches its upper-most point (or when it starts to move downward) to the time of release." Tempo can be measured in frames. Below is Yankee pitcher Ian Kennedy:
Kennedy's tempo is basically the definition of average. Frame 5 is when his knee reaches its upper most point before heading downward. Frame 31 is when Kennedy finally releases the ball.
31 - 5 = 26 frames, which means Kennedy's tempo is 26 frames. This gives Kennedy what is essentially an average tempo. Not fast to the plate, but not necessarily slow either. Below is a general reference for how you can classify varying speeds of tempo:
21 Frames or Less - Very Fast Tempo
22 or 23 Frames - Fast Tempo
24 or 25 Frames - Pretty Fast Tempo
26 or 27 Frames - Average Tempo
28 Frames or More - Slow Tempo
Examples of pitchers with fast tempos: Roy Oswalt and Tim Lincecum
Example of a pitcher with a slow tempo: Aaron Harang
Another example of a slow tempo pitcher is Florida Marlins prospect Brett Sinkbeil. One of the major reasons for his slow tempo is the fact that he is a "tall-and-fall" pitcher that reaches his "balance point" and then falls toward home plate as opposed to "drifting through his balance point", something that Lincecum does extremely well.
Keep in mind that tempo is just one of aspect to producing velocity. Just like a slow tempo does not mean a pitcher can't throw for a high velocity. By itself, a fast tempo does nothing. Combine a fast tempo with other components and a high velocity can be easily produced.