When should a coach be let go?

There was this piece yesterday, calling for Arizona coach Niya Butts to be replaced by basketball legend Cheryl Miller:

In seven seasons, coach Niya Butts is 89-128 overall and 31-95 in Pac-12 games. She made progress in her first three years, going 21-12 for a WNIT appearance in 2010-11. Since then, the Wildcats have finished 15-17, 12-18, 5-25 and 10-20.

Butts is under contract for one more season. There's no justification for an extension so UA Vice President for Athletics Greg Byrne can either play it out with a lame-duck coach hoping for some kind of lightning in 2015-16 or make a change now.

The University of Oregon also chose not to pay out former lame duck (no pun intended) coach Paul Westhead's contract, letting him serve the last miserable year of his overpaid contract through 2013-2014.

The question begs: when should a coach be let go?

I've been critical for several years of Washington State's decision to keep June Daugherty. She went into this season, her eighth with the program, with a 73-146 record. Isn't that enough proof to fire someone? Apparently not; the Cougars extended her contract last year.

How about Santa Barbara coach Carlene Mitchell? The team record has declined each of the four years she's been there, including this year's dismal showing of two wins. Should she be given another chance, or cast aside? This is her first head coaching position; her record coming into the year was 41-55.

Seattle University coach Joan Bonvicini has been at the helm there since 2010, and she had successful seasons her second and third years. How much more time should be given to prove herself?

It's a valid question in a rapidly-moving age where results are expected quickly and financial considerations are paramount. It took Pat Summitt 13 years to win her first national title; these days, a coach would be gone long before that time.

I maintain that the degree of coach retention has at least something to do with how a school values their women's basketball program. USC gave Michael Cooper only four years before moving on and hiring someone else.

What coaches do you think should be shown the door, and which should be given more time?