It has never been characterized as "chronic" by anyone official that I have seen. The team has only reported it as "an undisclosed injury".
But, this article from December, after Evansville's first MVC game said-
"Turnbull was held out of the game with what is being called a knee injury."
sports.yahoo.com
And the beat writer for the Evansville Courier & Press wrote this in late February-
"Connor Turnbull, last year's MVC Defensive Player of the Year, has only played twice since Jan. 4 with a nagging knee issue"
Maybe with an extended rest period, he might be able to return in good health. But any team that considers signing him would want to know more about his knee issue.
But, this article from December, after Evansville's first MVC game said-
"Turnbull was held out of the game with what is being called a knee injury."
Evansville men’s comeback falls short in MVC opener
EVANSVILLE, Ind. (WEHT) — After trailing by as much as 15 in the first half, the University of Evansville men’s basketball team cut the deficit to one before losing 83-78 in their Missouri Valley conference opener against Belmont. The Purple Aces came out of the gates slow Tuesday night falling...
And the beat writer for the Evansville Courier & Press wrote this in late February-
"Connor Turnbull, last year's MVC Defensive Player of the Year, has only played twice since Jan. 4 with a nagging knee issue"
Maybe with an extended rest period, he might be able to return in good health. But any team that considers signing him would want to know more about his knee issue.