Caitlin Clark has always been a baller, but even her own high school coach, Kristin Meyer, never saw this level of stardom coming, telling TMZ Sports, "I can't say that I honestly predicted this!"

Don't get it twisted, Meyer knew from the get-go Clark was special and would find success -- but No. 1 college women's basketball player ever simply didn't cross her mind when she had the point guard runnin' pick and rolls at Dowling Catholic High School in West Des Moines, Iowa.

"This level of success, and especially this level of fame that she's achieved," Meyer said, "it's just something I don't think anyone could have predicted."

Meyer, though, certainly saw the makings of it ... telling us Clark saw the game so well and displayed such a high basketball IQ, she would give her freedom on the court that other players didn't receive.

Meyer said Clark had rare traits off the hardwood too -- glowing about the sharpshooter's smile ... as well as her passion.

Meyer revealed Clark almost never made it to the University of Iowa, too ... explaining to us Clark was recruited heavily throughout her career -- and had seriously considered both Iowa State and Notre Dame before landing on the Hawkeyes.

Now that her college career is over, Meyer is looking forward to seeing what Clark will do with the Indiana Fever in the WNBA ... telling us she's excited to watch how the 22-year-old will adapt once professionals are around her.

As for a message Coach had for her former player, Meyer kept it sweet -- "We're proud of you. We're excited to see what you can accomplish next, and enjoy the whole process."