The spring came in like a lion for the 6-7 Diebler, who was busy leading the Rams to a Division II state championship while averaging over 30 points a game in victories over Dayton Dunbar and Wooster Triway. It went out like a lamb a couple of months later when he was diagnosed with mononucleosis.
But through it all, Diebler, who committed to Valparaiso in the middle of his sophomore season kept an even keel, and now he has to consider all of his options in regards to his future.
"Well, at this point, he has made a verbal commitment to Valpraiso and he has told Homer Drew a few months ... well, just before the AAU season had come, that he was going to look at the three schools," Jon's father and head coach, Keith Diebler said Friday evening in an interview. "He didn't want to have any regrets so he wanted to talk to a few schools."
"Yes, those are the three he's talked to," he confirmed of his son's options.
Shortly following his heroic performance at the Value City Arena in Columbus for the state final four, Diebler picked up right where he left off in early April, starring with 26 points a game for the All-Ohio Red AAU team at the Boo Williams tournament in Hampton, Va.
After that tournament, Diebler had some up and down moments struggling with his shot and stamina for several weeks, but by early June, the Dieblers had found out he was playing with mono for at least a couple of weeks, probably affecting his play.
"He got an MVP in a tournament in AAU and we thought he played with it," Diebler said in hindsight. "We just think he was in such tremendous shape he started out well with it, and then it got him down and it affected his play."
As Diebler continues to get back slowly from the illness, which attacks the body's immune system, and often causes the person to suffer from constant fatigue, he has started to look seriously at the three other schools involved.
The month began with Diebler visiting N.C. State, and last weekend, he took an unofficial visit to Ohio State. He will wrap up his visits with a trip to Ann Arbor next weekend for the Michigan-Notre Dame football game, but he's been to Michigan once already.
"Right now, he just came off mono this summer and he's starting to get pretty healthy," Diebler said. "The focus I think for him right now is getting ready for his season. He's visited those three places. He's doing some soul searching, some thinking."
In addition to missing some tournaments this summer after being diagnosed, Diebler was also forced to miss the Ohio State team camp that Upper Sandusky attended. Diebler made the trip and got a chance to talk to the staff at that point in late June, but didn't get to play.
Now Diebler is primed and ready for the season. First, he will have to forego cross country season to get properly in shape for basketball.
"He was cleared and then just informed not to run cross country now," Diebler explained. "He (the doctor) just thinks with the enzyme test just coming back, the blood test, that he (Jon) needs a little more work. He's pretty much working on his own, getting up every morning and getting ready for basketball."
Last season, Diebler made second-team All-Ohio in Division II, averaging 24.9 points a game. He committed to Valparaiso, joining his brother, Jacob, who averaged 18.8 points a game.
His brother is enrolled at Valparaiso, and is set to begin classes on a full scholarship this year as a freshman.
The Rams need Diebler to step up this season, as they lose four starters from a squad that finished 28-0 and averaged 90 points a game.
"We're just being a little more cautious because we want him for the season. We don't want to lose him," Diebler said. "I don't think that's a problem. We know it's a role he will relish being a leader. He's a junior and he's ready."
Now it's time for Diebler to continue getting back into shape, in which case he still has a lot of decisions ahead. Like any amusement park, keep your hands inside the vehicle until it comes to a complete stop.