Dan Rather says he wasn't shocked to learn Urban Meyer is retiring ... telling TMZ Sports it's clear to him the Ohio State coach NEEDS to focus on his health.
Urban and the Buckeyes announced Tuesday the coach will hang up his headset after the team's Rose Bowl game next month ... and Rather thinks it's easy to see why.
"I had the impression this last season that his health was not as good as he liked it to be."
In fact ... the CBS News legend says he thinks the rigors of the Zach Smith controversy really took a toll on the coach who once left a job at Florida because of complications with a brain cyst.
Ohio State says it'll replace Meyer with offensive coordinator Ryan Day ... but Rather tells us he doesn't necessarily think this is the end of Meyer's run on a football sideline.
"Who knows? He may yet come out of retirement and coach again."