Every coach has felt this tension: make a drill easy enough that players succeed, or hard enough that they're actually challenged. Most coaches guess. Mark Guadagnoli, a motor learning researcher at the University of Nevada Las Vegas, doesn't guess — he spent years measuring it.
His framework, called the Challenge Point Framework, gives coaches a principled answer to how difficult a drill should be — and it explains why both too-easy and too-hard practice are equally problematic, just in different ways.
The core principle
Guadagnoli's research established that learning is maximized at a specific level of challenge — not too easy, not too hard. The zone of optimal challenge produces the most durable skill acquisition. Outside this zone in either direction, practice time is less efficient.
The practical number that emerged from this research: roughly a 70% success rate during practice produces the best long-term learning outcomes. Players should succeed about 7 out of 10 reps. Fewer than 5 out of 10 means the drill is too hard — the challenge exceeds the player's current ability and they cannot extract useful information from their failures. More than 9 out of 10 means the drill is too easy — there is not enough challenge to stimulate adaptation.
Why too easy is a real problem
The "too easy" failure mode gets less attention than the "too hard" one, but it is more common in youth baseball. Line drills where every player fields a perfect chest-high toss from 15 feet. Batting practice where the coach lobs slow balls over the middle until the bucket is empty. Throwing drills at distances so short that no one ever misses a target.
These drills feel productive because players are succeeding and moving. But Guadagnoli's research shows that high success rates in practice correlate with low retention when conditions change — such as in a game. The brain adapts only when it encounters challenges it cannot immediately resolve. When a drill is easy, the brain doesn't need to adapt. It just replays the existing pattern. Nothing new is encoded.
Why too hard is also a problem
On the other side: a drill where a 9-year-old fields sharply hit grounders from 5 feet away and misses 8 out of 10 is not challenging — it is discouraging. Repeated failure without the ability to find a solution produces what psychologists call "learned helplessness" — the belief that one's actions don't make a difference. Players in this state stop trying to figure out what's wrong and begin to avoid the activity altogether.
This is the developmental danger of putting kids in situations that are far beyond their current skill level and hoping they "rise to the challenge." Some will. Most won't — and the ones who won't will associate baseball with failure and leave the sport.
How to use this in a practice
The 70% rule requires coaches to observe and adjust in real time. It's not a formula you apply once — it's a question you ask continuously during practice: are they succeeding or failing, and at what rate?
For fielding: if every player is cleanly fielding every grounder, move closer, add speed, or add a decision (where do you throw?). If more than 3 out of 10 are resulting in errors, slow the ball down, move the fielder closer, or remove the decision.
For hitting: if every player is making contact off the tee consistently, add a variable — two locations instead of one, tee slightly off-center. If players are failing to make contact regularly, move the tee back to a simpler location.
For throwing: if every throw is hitting the target, extend the distance or add a time pressure element. If throws are consistently off-target, shorten the distance or remove the pressure.
The interaction with skill level
One of Guadagnoli's more sophisticated findings is that the optimal challenge point changes based on skill level. A beginner needs more information per rep — and therefore benefits from practice conditions that are somewhat more predictable and consistent. An advanced player already has reliable basic patterns and needs more variability to keep developing.
This means the same drill can be appropriately challenging for one player and too easy for another on the same team. The solution is differentiation: adjusting the drill constraints for different groups within the same practice. Move the better fielders to a different position that creates harder plays. Give the beginners a simpler version of the same drill concept.
The connection to player confidence
There is a psychological dimension to the challenge point that research supports beyond motor learning. Players who experience roughly 70% success — enough challenge to feel the game is hard, enough success to feel competent — report significantly higher confidence and enjoyment than players in either extreme. The feeling of being challenged and succeeding is intrinsically motivating in a way that easy success and constant failure are not.
This is why the best practice designs feel a little bit hard. Players feel like they earned the successes rather than being handed them. That feeling — of genuine mastery rather than manufactured success — is what keeps players coming back.