What is arm strength?
Per Statcast, arm strength is measured by average baseball velocity of a player’s fastest throws. The specifics vary by position.
The following two quotes are from Baseball Savant.
Definition of arm velocity. “Statcast position player arm strength metrics are available beginning with the 2020 season. Given that there is no rulebook definition of “a throw where the player is trying hard,” and many non-competitive lobs are captured, we have elected to take the average of the top portion of a player’s throws. Since the demands of each position grouping are different, the averages and qualifiers are different as well.
1B — average of top 1% of throws — minimum 100 throws to qualify
2B/SS/3B — average of top 5% of throws — minimum 75 throws to qualify
OF — average of top 10% of throws — minimum 50 throws to qualify”
Catchers: From Pop Time Leaders. “Arm strength is measured on “max effort” throws, or the average above a player’s 90th percentile performance.”
Do best Diamondback defenders have the strongest arms?
Although I anticipated that the best defenders would tend to have the strongest arms, it appears not to be the case. The following table seems to show that arm strength and defensive skill have very little correlation.
Throwing involves many muscles working in coordination. The muscles include shoulder muscles, deltoids, triceps, latissimus dorsi, abdominals, and quadriceps per this article.
Aligning the shoulders in the direction of the throw is important per Frank Moore in this MLB.com video.
There may be a tradeoff between velocity (the measurement of arm strength) and accuracy. A study of professional handball players found that when they focused on accuracy, their velocity was reduced about 15%.
The wrist is an important factor. When I threw a softball while playing softball, my experience was that the accuracy of my throw was greatly impacted by my wrist. Although hitting a pickleball is different than throwing, my observation of wrist importance was strengthened because if I rotate my wrist just before impact it changes the direction and if I flip my wrist it adds extra velocity.
Arm strength is better than MLB average for which Diamondback positions?
The following table shows arm strength by position and MLB rank among qualified players at that position.
In addition to third base, Diamondbacks’ arm strength is above average at second base, left field, and right field.
Per my baseball general knowledge, arm strength is most important at third base and right field due to the need for long and hard throws. At third base, the Diamondbacks have three players (Alcantara, Rojas, and Rivera) with above average arm strength. At right field, Jordan Luplow had above average arm strength.
An unexpected observation is that the MLB average arm strength in center field is nearly as high as right field. Is arm strength in center field more important than I realized?
Have arm strengths improved this season?
With many new Diamondbacks, the answer is likely incomplete. And position played sometimes made a difference. This season Ketel Marte’s arm strength was greater than 2020 (when he played second base), but it was less than 2021 (when he played center field and second base). Sometimes outfielders get a running start before they throw the baseball. The following Diamondbacks increased their arm strength.
- Christian Walker: his arm strength increased from 73.3 mph to 75.1 mph.
- Carson Kelly: his arm strength increased from 80.9 mph to 81.6 mph.
- Daulton Varsho: his arm strength increased from 81.8 mph to 84.4 mph.
- Emmanuel Rivera: his arm strength increased from 85.9 mph to 91.0 mph.
- Sergio Alcantara: his arm strength increased from 89.4 mph to 92.4 mph at third base, 94.1 mph at shortstop.
- Jordan Luplow: his arm strength increased from 88.8 mph to 94.6 at right field.
Who has more arm strength: Christian Walker or Paul Goldschmidt?
Compared to fielding other positions, when fielding first base arm strength is less often important. Nevertheless, a comparison of Paul Goldschmidt, previously the Diamondbacks’ first baseman and Christian Walker, the current Diamondbacks’ first baseman, shows Christian Walker had higher arm strength (75.1 mph vs 66.9 mph) and better defense. better defense was 17 DRS and 15 OAA at first base compared to 2 DRS and negative 6 OAA. Chirstian Walker is the best defensive first baseman in the Majors, and arm strength is a significant part. Arm strength of fielders matters.
Batting is another story. Despite a weaker arm strength, Paul Goldschmidt is a better batter than Christian Walker (.421 wOBA vs .343 wOBA). Interestingly, on 30 September, they each had exactly 642 PAs, with Walker having a very slim lead in home runs (36 vs 35).
Arm strength is measured by average baseball velocity of a player’s fastest throws. For the Diamondbacks, arm strength and defensive skill have very little correlation. It would not be a stretch to say wrist and muscle coordination are needed to achieve accuracy in defensive throwing.
The Diamondbacks have above average arm strength in positions where it matters, such as third base and right field. In addition, they have above average arm strength at second base and left field.
This season, arm strengths improved for at least six Diamondbacks.
Although arm strength at first base is less often important, Christian Walker had better arm strength than Paul Goldschmidt, which is one of many reasons Christian Walker is the best defensive first baseman in the Majors.