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The gap between two twelve-year-olds

This season we put 156 athletes through tryouts, scored by fifteen coaches on the same rubric. When it was over, we pulled the numbers: anonymized age-group averages, nothing tied to a single kid. Most of it confirmed what any coach would guess. Older players hit the ball harder and throw harder. One number didn't.

Two twelve-year-olds, forty-six miles an hour apart

At 12U, the hardest ball hit off the tee registered 81 mph of exit velocity. The softest, from a player the same age at the same tryout, was in the mid-30s. That's not a mis-entry, and it isn't two different sports. It's two kids who will stand in the same batting order.

Put a number on the range. Exit velocity inside our 12U group spanned about 46 mph, top to bottom. Now compare that to how much the average moves as kids grow up. The gap between the average 10U (53 mph) and the average 14U (73 mph), four full years of development, was 20 mph.

The spread inside a single age group was more than double the climb across four years of them.

The averages do climb, cleanly

None of that means age is meaningless. Line the age groups up and exit velocity marches exactly the way you'd hope:

Age groupAthletesAvg exit velo
10U1552.7 mph
11U1462.8 mph
12U2461.2 mph
13U2067.4 mph
14U1972.7 mph
15U975.4 mph
16U581.4 mph
Off a tee, one program's 2026 tryouts. Each athlete's measured exit velocity, averaged within age group.

Arm strength tells the same story. Infield throwing velocity and fastball velocity both climb about three to four miles an hour a year through the middle of the age range, then jump as the older kids hit their growth:

Age groupINF throw veloFastball velo
10U48.1 mph46.7 mph
11U48.8 mph47.7 mph
12U53.5 mph49.7 mph
13U59.6 mph55.1 mph
14U62.4 mph59.1 mph
15Un/a71.2 mph
Averages by age group. Between 6 and 35 athletes per cell. The 15U groups and up run small enough to read as directional, not gospel.

The tool that didn't grow up

Not everything climbs, and that's the part that surprised us. Home-to-first times were essentially flat, right around 4.3 seconds at every age from 11U through 15U.

Some of that is the field growing up with the kids. Bases sit farther apart as players age up, so a faster older athlete covers more ground in about the same time. But even allowing for that, the pattern held. The tools that separate players by age are the ones you measure in miles per hour, in the bat and the arm. Raw foot speed is spread far more evenly across the ages than you'd think.

Before anyone quotes these at a tryout

A few things to be clear about, because numbers like these get pulled out of context:

What the spread is telling you

You stop treating a birth year as an evaluation. Age tells you where to set the bar. It doesn't tell you who clears it. The player walking into a 12U tryout could be the 81-mph outlier or the 35-mph one. The only honest way to find out is to measure him the same way you measured everyone else, and write it down so the decision holds up when someone asks about it three days later.

This data is a byproduct. We didn't set out to run a benchmark study. We set out to make tryout cuts we could stand behind. The numbers are just what falls out the back when a full staff scores every athlete the same way, for a whole season.

Running tryouts this season? DiamondAudit gives your staff one scoring standard and a record behind every cut.

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