The first time I saw Bill Walsh at work, he was cussing up a storm.

For much of Western civilization, the everlasting image of Walsh was the ultimate football sophisticate. He was a silver-haired genius who could make X’s and O’s dance on a chalkboard. He was urbane and professorial, a debonair 1980s contrast to those knuckle-dragging Neanderthals from the ’40s, ’50s and ’60s.

Yet on this otherwise calm fall afternoon with the commuter rail trains rumbling in the distance and low-flying jet engines roaring overhead, the loudest noise on the San Francisco 49ers practice field 21 years ago was the legendary Walsh stalking around the field in a profanity-laced, old-school snit.

“Dammit, run it again! RUN IT AGAIN!!!”

“AGAIN dammit!! Joe, this is a precise route. I don’t want the ball here. I don’t want the ball here, either. I want the ball RIGHT HERE!!!! Now run it AGAIN!!”

This is how I will always remember the late, great Hall of Fame coach who passed away at the age of 75 after a lengthy battle with leukemia: cussing out another future Hall of Famer at the top of his game. This profane rip on Joe Montana was the essence of the man’s coaching genius.

You had to be there to see how insistent Walsh was about why Montana had to throw a timing route a particular way to Jerry Rice, who was slashing up field on a seam route. Walsh saw these slightly wayward passes as an affront to his precise X’s and O’s, even if a future Hall of Fame quarterback was the one throwing them. For his West Coast offense to run as fluidly as a Swiss timepiece, things needed to be executed flawlessly. Footwork was essential. Timing was everything and repetition was king.

And Walsh, always the great teacher, demanded perfection.

He would spend hours on end behind closed doors detailing his coaching hieroglyphs, scribbling X’s and O’s all over the place in one imaginative scheme after another.

“Basically, in the era of modern professional football, no one had more influence on the way offenses are played in the game than Bill Walsh and Don Coryell,” said Jim Hanifan, another legendary coaching voice of the last half century. “Coaches by nature plagiarize. If someone does something that works, everyone copies it. Well, over the last 50 years, lots of coaches have copied things that Bill Walsh does. Just look around the NFL and see how many guys are running some variation of Walsh’s offense.”

I was lucky enough to have many football conversations with Walsh over the years. We talked about his offense. We talked about his eye for finding and coaching great quarterbacks. But one of the best conversations I ever had with Walsh was how he crafted one of the most reliable coaching bloodlines in NFL history.

As he built his coaching tree, Walsh embraced an open-door hiring policy that gave opportunity to black coaches at a time when the rest of the NFL was in the Stone Age concerning minority hiring. From groundbreakers such as Dennis Green to neophytes such as Mike Tomlin, nearly every black head coach in NFL history has a direct or indirect historic link to Bill Walsh.

The football world may remember Bill Walsh and his X’s and O’s as the catalyst for changing the face of the NFL. But to me, Walsh was a rarity for a man of his times, someone who was equally interested in changing the face in another way. The West Coast offense was the religion he spread throughout the game, but Walsh ought to also be remembered for spreading the far more significant gospel of equal opportunity.