Checking on pitch velocities

"The old saying in baseball is that the radar gun gets you drafted, but you have to pitch to get to the big leagues."

- Roy Clark, Braves Chief of Scouting

Every baseball fan knows that a pitcher's velocity is important. It's often the first thing the casual fan looks for, and when the radar gun starts nearing triple digits, it's easy to become very excited.

We can explain logically why fastball velocity is important—throwing it faster gives the hitter less time to react and makes him more likely to make poor contact, or no contact at all. More recent work has confirmed that velocity is important in generating whiffs on fastballs, and indirectly, on changeups.

When analyzing fastball velocities, it's important to remember that a pitcher's velocity will generally decrease each season as soon as he turns 21. So, the best case for a pitcher, from year-to-year, is to maintain or minimize the loss in velocity. It's also important to take the month into account. Fastball velocity for pitchers tends to be lower early in the season, and then gradually increases, as this chart by Mike Fast at Baseball Prospectus shows:

Below is a graph showing the changes in Rays pitchers' fastball velocities. The light blue bar represents the change in velocity from 2014 to 2015, and the dark blue bar represents the change in velocities from April 2014 to 2015. Geltz and Karns didn't pitch in April 2014, so they don't have a comparison for that section.

• I'm more concerned about pitchers who have a large decrease in both categories, like Ernesto Frieri. This suggests that his low velocity at the start of this season isn't because he's a perennial "slow starter", and could be a sign of a larger problem.

• While Kevin Jepsen has lost significant velocity from his average last year, I'm less worried about him because his velocity has shown to increase as the year goes on. Although it did start lower this year than it did in 2014, it's not as large as the -1.41 mph velocity difference from 2015 may suggest.

• As Adam pointed out on Saturday, Drew Smyly's velocity dropped off significantly during his last start. This most likely was from his injury, and it'll be important to watch his velocity once he returns.

• Chris Archer has shown increased velocity from 2014, which is very encouraging. Even though this contradicts typical pitching aging curves, it may stem from a change in mechanics or growth as a pitcher.

• It may look concerning that most of the Rays have decreased fastball velocities, but there's a chance that the data makes the problem look worse than it actually is. A small decrease in velocity from year to year is expected as pitchers age, so it'd be foolish to expect 2015 velocities to mirror those of 2014.

Other Pitches To Watch

As the season progresses, I'll be paying most attention to Ernesto Frieri and Brandon Gomes, because their velocity decrease is the greatest and it looks unlikely to rebound. The bullpen is shaky as it is, and a collapse in performance by Frieri or Gomes would be crippling.

Analyzing other pitches can be difficult, because pitchers don't always want more velocity on their off-speed pitches. But, there are some early trends that are worth watching.

Chris Archer has been throwing his elite slider harder in 2015 than in past seasons.

Running simple regressions of PITCHf/x data against whiffs and groundball rates indicates that velocity is positively correlated with both results. This means that more velocity should make Archer's slider even more effective. So far, this has proved true; his groundball rates and whiff rates on the slider have all increased in 2015.

Erasmo Ramirez has been throwing his changeup faster, and as Pavlidis' article explains, a greater changeup velocity will most likely lead to more groundballs. However, Ramirez' fastball velocity didn't increase in conjunction with his changeup, minimizing the velocity difference between the two pitches. Pavlidis' article also shows that velocity difference is significant in getting whiffs on changeups, so a smaller difference will most likely cause Ramirez to get fewer swings and misses.

Alex Colome has the opposite situation. His changeup has been slower this year, increasing the velocity difference, which would lead to more whiffs but fewer groundballs.

Overall, Rays' pitchers seem to be in decent shape with their velocities. While most pitchers are throwing their fastball slower than in 2014, for the most part the differences are small, and are what would be expected as pitchers age.  Gomes, Frieri and Jepsen have all seen significant drops in their velocity, and while I have confidence in Jepsen to bring it back up, their speed and corresponding performance is something to watch going forward.

On a positive note, Odorizzi and Archer are gaining velocity, and Archer's slider continues to develop into a nastier pitch. FanGraphs has the Rays' playoff odds at 25%, and lower fastball velocities for much of the bullpen adds more support to the notion that Archer and Odorizzi will have to carry the Rays if they are going to make a push for the postseason.

PITCHf/x data is from Brooks Baseball.