Bill Simmons -- Hey Shaq & LeBron ... Your TV Shows Will Probably Fail

Shaquille O'Neal ain't gonna be the next Seinfeld ... and LeBron James is no Alex Trebek ... so says ESPN's Bill Simmons who thinks both NBA stars are likely to crash and burn with their new TV projects.

As we previously reported, Shaq's got a sitcom in the works based on his real-life business empire ... and LeBron's production company is partnering with NBC to create a new primetime game show.

But Simmons tells TMZ Sports ... neither venture looks promising -- "I wouldn't invest in either of those."

Simmons on Shaq -- "I don't have a lot of high hopes for that sitcom. I don't see the sitcom thing happening."

Simmons on LeBron -- "I think game shows usually don't work. I probably have more high hopes for the Shaq show."