I will second your call for Jim Sweeney as an underestimated coach. His 1972 team with Ty Paine and Ken Grandberry knocked off #20 Stanford and #17 Washington and finished ranked 19th in the nation. The previous year also beat #10 Stanford at Stanford.
At Fresno State he took them to seven bowls, winning five of them. In his nineteen years there he won nine or more games a year eight times.
His first three years at WSU were rough. But after that his teams were tough and competitive. Apple Cups were evenly split, with a high point of winning 52-26 in 73. And he was respected and well regarded.
My favorite Coach Sweeney call was the 71 Oregon game at Joe Albi which I attended. The Cougars, down by four in the fourth, were punting from the Duck’s 46. The ball was instead snapped to the fullback, Ken Grandberry. He slid the ball ahead and between the back legs of halfback Bernard Jackson. Wide reciever Don Transeth (now a WSU foundation trustee) swung from the left, took a fake hand off from Granberry, and with team blocking, took the Oregon team to the far right side of the field. Jackson remained in the blocking position, holding the ball hidden under his crouched body, until the left side of the field was vacated. He then ran 46 yards all alone. A fine win.
Members the 71 team eventually had eight drafted.
I wish he had stayed longer.