Accompanied by assistant coach Brandon Miller, Diebler gets in about half an hour's worth of extra work before the team assembles for practice. It is just one example of how Diebler has grown from Ohio's all-time leading prep scorer to the player who will likely soon become the most prolific three-point shooter in Big Ten history.
"He's the first one in the gym (and) he's the last one to leave," Miller told BuckeyeSports.com. "He is an extremely hard worker and you can't be as good a shooter as he is without being that way."
The numbers back up Miller's words. Heading into Saturday's road contest with Wisconsin, Diebler's name already dots the school's record book. He has already shattered the OSU record for most three-pointers in a career (328 and counting), has two of the three most prolific individual seasons from beyond the arc and has tied the program record for most treys in a game.
Diebler has hit a three-pointer in 39 straight games and has steadily climbed the conference ranks. Officially, he trails only two players: Penn State's Pete Lisicky, who hit 332 three-pointers from 1994-98, and Michigan State's Shawn Respert, who hit 331 from 1991-95. Michigan's Louis Bullock finished with 339 three-pointers during a career that lasted from 1996-99, but the conference does not recognize his mark due to NCAA sanctions.
As an assistant during Lisicky's freshman season, current PSU head coach Ed DeChellis said he sees similarities between the former Nittany Lion and current Buckeye.
"Pete was a great shooter, really a picture-perfect shot like Diebler's," he said. "One thing that guys who can really shoot the ball, they all have great form and they shoot it textbook. I think they have an air of confidence about their shot."
Diebler did not get there without having to make a number of adjustments along the way. As a freshmen, he endured one of the most-scrutinized shooting slumps in recent memory, connecting on 48 of 166 (28.9 percent) of his three-point attempts.
In addition to adjusting to the collegiate game, Diebler had to make an adjustment that is much more difficult than it sounds: he had to adapt to catching and shooting rather than shooting off the dribble. As his team's primary offensive weapon at Upper Sandusky, Diebler was accustomed to always having the ball in his hands.
"We were catch-and-shoot but never a lot of coming off screens," said Keith Diebler, Jon's father and prep coach. "I think he's coming off screens more. He'll still catch and shoot off the break sometimes when they've got numbers but there's definitely a transition."
Not only that, but Dave Richardson, the team's associate strength and conditioning coach, noticed that Diebler suffered from a lack of hip flexibility. That, in turn, impacted his ability to consistently shoot the basketball.
"Jon has worked really hard in improving his base and being able to sit down in a stance," Miller said. "He is much better in his shot prep and being lower, ready to shoot the basketball now than he was when he first arrived. I think that has a huge part to do with his success."
Diebler's father, who is not coaching this season, said he worked on flexibility with his players after his son left after seeing Jon struggle.
The numbers quickly came around. As a sophomore, Diebler's 116 three-pointers set the school record. He passed former career leader Jamar Butler (2005-08) and his mark of 242 treys before his junior season was complete. Miller said it has helped that Diebler has played with players such as Evan Turner and Jared Sullinger, Buckeyes who have drawn plenty of focus from opposing coaches.
However, the senior has had to do more than stand around and wait for the ball to come his way, the coach said.
"Jon's also a guy who can sprint off a screen, hit on his inside foot and shoot it in," Miller said. "Jon's also the guy who's been able to come off the bounce and shoot it in. He can shoot threes in a variety of different ways and I think that's part of the reason whey he's going to end up breaking this record."
As Diebler's dad pointed out, his son became a three-point shooter for the Buckeyes because it was what head coach Thad Matta needed him to do to help the team.
Said Matta: "When he came in here he shot it well, he just didn't shoot it well in games. You knew him as a kid and how hard he was going to work and the thing he was going to do to get better."
Now he figures to go down as the best ever in Big Ten history. But according to his father, reaching that mark is far from the primary goal.
"The bottom line is going into every game, giving it everything you've got and understanding the game and winning," Keith Diebler said. "I think he'd trade everything he's ever done for a national championship as far as records. Winning the Big Ten, winning the Big Ten tournament, those are the things (he wants)."