He’ll be remembered most for that which can’t be measured or even accurately explained. Sure, we have plenty of facts and figures we can use to celebrate the great baseball career of Bob Gibson -- the wins, strikeouts, shutouts, Cy Youngs, Gold Gloves and the World Series superlatives.

But it’s the competitiveness Gibson conveyed and the intimidation he inspired that truly shaped his legacy in this sport. And those are the qualities that we remember most now that he passed away Friday after a battle with pancreatic cancer. He was 84. The Cardinals, the team on which he spent his entire 17-year career, confirmed the news Friday night.

Gibson's passing comes on the anniversary of one of his greatest games -- his 17-strikeout performance in Game 1 of the World Series on Oct. 2, 1968 -- and less than a month after the death of Lou Brock, a fellow Hall of Famer and Cardinals teammate from 1964-75.

"This is a very sad day for all of Baseball," MLB Commissioner Rob Manfred said in a statement. "Bob Gibson produced one of the most decorated pitching careers in history with his intelligence, athleticism, durability and toughness. One of only three players to be a two-time MVP of the World Series, this legend of October will always be remembered as one of our sport’s fiercest competitors. His performance in 1968 with the Club he represented all his life, the St. Louis Cardinals, is on the short list of the best pitching seasons ever.

"Bob was a loyal friend to many people throughout the National Pastime, and he will be deeply missed. On behalf of Major League Baseball, I extend my deepest condolences to Bob’s family, friends, Cardinals fans, and all those who respected one of the greatest pitchers who ever lived."

• Top 10 moments in Bob Gibson's HOF career

How does one describe what made Gibson one of the greats? His old teammate Joe Torre was once asked that question.

“Try pride, intensity, talent, respect, dedication,” Torre said. “You need them all.”

“Bob Gibson was arguably one of the best athletes and among the fiercest competitors to ever play the game of baseball,” said Cardinals principal owner and CEO William O. DeWitt, Jr. “With yesterday being the anniversary of his record-setting 17 strikeout World Series game in 1968, it brought back many fond memories of Bob, and his ability to pitch at such a high level when the Cardinals were playing on the games’ biggest stages. Even during the time of his recent illness, Bob remained a strong supporter of the team and remained in contact with members of the organization and several of our players. He will be sorely missed.”

• October brought out the best in Gibson

Don Sutton once said Gibson “hated everyone, even Santa Claus.” Gibson’s former catcher Tim McCarver described him as having “eyes smoldering at each batter, almost accusingly.” Dusty Baker once said the only two people he ever felt intimidated by were “Bob Gibson and my daddy,” and when Baker was preparing to face Gibson during Baker’s time with the Braves, Hank Aaron gave him some advice.

“Don’t stare at him, don’t smile at him, don’t talk to him,” Aaron said. “If you happen to hit a home run, don’t run too slow, don’t run too fast. If you happen to want to celebrate, get in the tunnel first.”

Indeed, Gibson was often depicted as the meanest man to ever take the mound, his low-slung cap and crabby countenance pairing with a vicious slider and two variations of a fiery fastball to make for a truly imposing presence. He’s been painted as a bully with the baseball, unafraid to go up and in against any hitter who dared disturb him by inching too close to his precious plate.

Such labels were intended to lionize Gibson for his killer instinct.

But the man himself resented the reputation.

“I wasn’t trying to intimidate anybody, are you kidding me?” he once told Joe Posnanski. “I was just trying to survive, man.”

Pack Robert Gibson’s tale was one of survival.

Born the youngest of seven children in Omaha, Neb., on Nov. 9, 1935, and named after his father, who died shortly after his birth, Gibson suffered from rickets, asthma and a heart murmur as a child and needed permission from a doctor to compete in sports. That didn’t stop him from becoming a baseball and basketball star at Creighton University, where he was the school’s first African American athlete in either sport.

How good was Gibson on the hardwood? In 1957, even after signing with the Cardinals to play baseball, he suited up for the splashy, flashy Harlem Globetrotters, a marriage that certainly doesn’t jibe with Gibson’s no-fun, no-frills approach to pitching. But yes, he was quite good, which is why, as the story goes, the Cardinals had to give him an additional $4,000 to persuade him to give up basketball entirely.

Gibson played his earliest professional games in the southern United States at a time when it could not have been easy for a Black man. He endured those ugly experiences, as well as the difficulty of an initial exposure to the big leagues in 1959 and ’60 in which his stuff simply didn’t play up as well as it eventually would. On the mound, Gibson had some wildness that had to be corralled. Off it, he dealt with racial prejudices that affected his role. But by 1962, he began to assert himself as a star on a Cards club that had begun working to ease racial tensions.

“The initiative in building that spirit,” teammate Curt Flood once wrote, “came from black members of the team. Especially Bob Gibson. … [W]e blacks wanted life to be more pleasant, championships or not. … It began with Gibson and me deliberately kicking over traditional barriers to establish communication. … After breaking bread and pouring a few with us, the others felt better about themselves and us.”

Soon, Gibson and the Cardinals reached the peak of their powers together. Gibson, who came to be known as “Hoot” or “Gibby,” followed up a 19-win season in 1964 by winning Games 5 and 7 in the World Series against the Yankees (the latter on two days’ rest) to claim the Series MVP honor. Three years later, he’d claim that prize again -- this time winning Games 1, 4 and 7 against the Red Sox. All three wins were complete games, as Gibson allowed just 14 hits and five walks while striking out 26, and he even homered in Game 7.

“[The 1967 Series] was his stage,” teammate Nelson Briles would later say. “He had the worldwide opportunity to display all he was and all that he had. In ’67, that’s exactly what it was for Bob Gibson.”

Gibson and the Cards came out on the wrong end of the result of the 1968 World Series against the Tigers. Gibson again went the distance in Game 7 -- making that his eighth complete game in nine career World Series starts -- but the Tigers prevailed, 4-1.

Still, the 1968 season is remembered as Gibson’s very best. He was the face of the “Year of the Pitcher,” posting a Major League-best 1.12 ERA with 268 strikeouts, 13 shutouts, 15 consecutive winning decisions and a stretch of 95 innings in which he gave up just two runs. He won both the Cy Young and the MVP Award that year, and he led a season so uniquely dominant from the pitching perspective that MLB took the bold step of lowering the mound the following year.

Gibson once told the St. Louis Post-Dispatch that he pitched that 1968 season with tremendous pressure.

“I think I developed ulcers then,” he said. “I had a lot of stomach problems and no one ever knew about it. My stomach was always tied in knots because it was always the sixth or seventh inning and the score was 1-0 or 2-1 or something like that, either behind or ahead. And you couldn’t relax. People thought I was relaxed, but I was tied in knots all the time.”

There would be another Cy Young in 1970 and a no-hitter against the Pirates in ’71. Gibson continued a stretch of nine seasons in which he won a Gold Glove, and he was proficient enough at the plate to hit 24 career home runs, plus two in World Series play, and have 30 career games in which he drove in more runs than he allowed. By the time his career ended in ‘75, he had accumulated 251 wins and 3,117 strikeouts with a 2.91 ERA across 3,884 1/3 innings pitched. He was a nine-time All-Star. He was respected enough in his retirement years to serve as a pitching coach for the Mets, Braves and Cardinals. He was a first-ballot Hall of Famer in ‘81 and an obvious choice for MLB’s All-Century Team in ‘99.

“Bob Gibson’s intensity and determination commanded respect and admiration from his peers on the field, as well as the generations of baseball fans who followed him throughout his career. His deep love and dedication to the game was felt by everyone he encountered, and nowhere more so than in Cooperstown, where he and his wonderful wife Wendy would return each summer, after his Induction in 1981. On behalf of the Board of Directors and the entire staff of the Hall of Fame, we send our love and deepest condolences to Wendy and the Gibson family. Bob’s spirit will live on forever at the Hall of Fame," Baseball Hall of Fame chairman Janet Forbes Clark said.

All of these facts and figures shape our understanding of what a force of nature Gibson was. But it’s the dogged competitive instinct -- the sheer ruthlessness -- that people remember most. And he brought that attitude toward his battle with cancer in his later years.

Gibson stood an unimposing 6-foot-2, 195 pounds during his playing days. He never understood why he got more compliments for being vicious than he did for being victorious. The numbers (Gibson never hit more than 13 batters in a single season and never even led his league in hit batsmen) tell us his image as an enforcer was probably exaggerated.

And that angry glare? Gibson told Posnanski that was just him squinting at the catcher’s signals because he needed glasses.

In the end, we can’t measure whether Gibson truly was the meanest or most intimidating pitcher of all time. But we can decisively say he was one of the very best.