To me, it's a combination of poor recruiting and poor training that has resulted in essentially a talent tailspin. If your players aren't in shape, they get drafted lower (Sullinger, Thomas, Ross, etc.), which in turn makes it hard to convince the top talent to come here because they'd rather go to places like Kentucky, Duke, Kansas, etc. where they are more likely to go in the lottery after their Freshman year.
Right now out of the top 26 2016 recruits (Rivals), 14 are committed to Kentucky/Duke/AZ/MSU/UCLA. OSU's #1 recruit is currently #59. You can't start with that big a talent disadvantage and consistently contend for titles. In 2015 OSU's top recruit was #44. OSU has had exactly 1 top 25 recruit since 2010, and it was D'Angelo Russell (#18). Talent wins.
Why would any of the top guys come here when OSU has had 1 "One and Done" since 2009? It's possible Thad doesn't want to go after the One and Done guys as much as someone who will stay here for 3-4 years, but that's just the wrong strategy in today's age. Wisconsin isn't who you want to model your program after, it's Kansas, Duke, Kentucky, etc. Place a premium on getting people to go high in the draft, and you'll continue to reload your program every year, and always be in contention for a title.