J.R. Richard never faded. His next to last start was at the All-Star Game in 1980. He was 30 years old, at the apex of his powers, when it all went away. He was the Sandy Koufax of his generation.

Richard died on Wednesday in Houston, at age 71. He never made the Hall of Fame, never won a Cy Young Award, never pitched in the World Series. He might have done all of those things, but a stroke abruptly ended his career and changed the course of his life.

“If I’d have kept on going,” he said by phone in 2015, “I’d have rewritten the history books.”

Instead Richard’s career totals, all with the Astros, are modest: 1,493 strikeouts, the same as Larry Dierker, and 107 victories, the same as Edwin Jackson. His legacy is the reverence of those who faced him, the wonder of what might have been.

“I kid you not: If they took the radar gun that they’re using right now and they put it on J.R., when the ball left his hand like that, it was probably going 110,” the longtime outfielder Gary Matthews, who faced Richard more than any other hitter, said on Thursday.

“If he doesn’t have that stroke, he’s in the Hall of Fame. He had Hall of Fame stuff and he would have had Hall of Fame stats. J.R. Richard doesn’t have to take a back seat to any pitcher that’s ever pitched in the major leagues.”

As a boy in Ruston, La., Richard would gather a pocketful of rocks and go into the woods, taking aim at birds and rabbits. His fastball came naturally then, but he learned his slider through something of a miracle: As a teenager, while taking a walk along U.S. Route 167, he found a pitching manual discarded by the side of the road.

Richard mastered the new pitch so quickly that the Astros drafted him out of high school with the second overall pick in 1969. Two years later he tied a record for strikeouts in a major league debut with 15 against the San Francisco Giants. He fanned Willie Mays three times.

“If you ask me who had the best slider I ever saw, it would probably be J.R. Richard,” said Pat Gillick, the Hall of Fame executive who scouted for the Astros in the 1960s. “I was down there when we signed him, and I thought he had the hardest slider, and the hardest slider to pick up, that I can ever remember.”

But Richard, like Koufax, would take years to find his footing — always hard to hit, but prone to walks and wild pitches. Then, also like Koufax, he finished with a five-year flourish before his body gave out at age 30.

According to Baseball Reference, the most similar player to Richard, through age 30, was Bob Gibson. But there was really nobody like him, at least until Randy Johnson came around, as a fastball-slider intimidator who stood so tall. Richard was 6 feet 8 inches, the tallest pitcher in baseball throughout his career.

Richard faced 16 Hall of Fame hitters for a total of 548 at-bats, the equivalent of a batter’s full season. Collectively they hit .245 off him, with 150 strikeouts. Everyone else combined to hit .209.

“He was unique in that he was so big, so tall, and his slider was so hard, like his fastball,” Mike Schmidt, who was 7 for 41 with no homers off Richard, said on Thursday. “From the right side of the batter’s box, it was very, very intimidating. You almost had to go into a defensive hitting mode — do anything you could to just make contact. It was a very unusual night when he pitched.”

Perhaps Richard’s career would have unfolded like Johnson’s. Both led their league in walks three times through age 28, but won strikeout crowns at 28 and 29. Both had their league’s lowest earned run average in the year in which they made their 200th career start.

In 1980, Richard was coming off consecutive seasons of 300 strikeouts. He was 10-4 with a career-best 1.90 earned run average at the time of his stroke. He had allowed only two home runs in 17 starts, and batters were hitting .166 against him. He overpowered the American Leaguers at the All-Star Game.

“I don’t think I was even in my prime when my baseball career ended,” Richard said, in that 2015 interview. “I kept getting better and better every year. I think I would have struck out 300 batters four or five more years.”

He added: “And another thing, as I look back on my career? I should have went to the New York Yankees. I’d have myself a couple of World Series rings right now.”

Richard might have gotten one with Houston in 1980, his first season with Nolan Ryan as a teammate. The Astros lost to the Philadelphia Phillies that fall in a thrilling best-of-five National League Championship Series, with four of the five games reaching extra innings. It is safe to think Richard could have made a difference.

“Just think about Richard and Ryan in the same rotation,” said Schmidt, then the Phillies’ centerpiece. “Crazy.”

As it happened, Richard had pitched his final game that July 14, when he left a shutout against the Atlanta Braves in the fourth inning in Houston. He had an upset stomach, but there was much more going on.

Richard had trouble seeing the catcher’s signs and had been complaining for weeks of a dead arm. He had asked for a month to rest, but only after the Atlanta start was he placed on the disabled list. He was found to have a blood clot blocking the primary circulation to his pitching arm, but was cleared for workouts.

On July 30, he collapsed at the Astrodome while playing catch. Surgeons saved Richard’s life, but the trajectory of that life changed forever.

“After the stroke, he was never, ever the same again, from the laughter, from the mannerisms, you could tell,” said Matthews, who was on deck when Richard threw his last pitch and remained a close friend. “He would be trying, but as far as I was concerned, from knowing him since we were in the minor leagues, he was a totally different person after the stroke — and who wouldn’t be? He was almost lucky, through the grace of God, to be able to live.”

Richard tried a comeback in the minors, and later in the Senior Professional Baseball Association, but he was too wild to stick. He sold cars and mobile homes for a while, lost money in bad investments, endured a second divorce. He lacked the stamina to stay in shape and struggled with depression. He had no health insurance and was too young to start receiving his major league pension.

In late 1994 and early 1995, Richard was sleeping on a board under a bridge overpass at 59th and Beechnut Streets in Houston.

“You get used to the sound of the cars going overhead, because you become so fatigued, so tired — when you lay your head, you be gone,” Richard said in the 2015 interview. “I had some people I knew when I was playing ball and I would go to their house and wash my clothes and eat, maybe spend a night or two. But some of those people had families and I did not feel right just coming in. So I would go under the bridge, and that’s it.

“Everything at that point became a point of survival. You’re trying to survive, you have no transportation, no food, no finances. You ask yourself a lot of times, where do I go from here?”

Richard made it out, with help from friends and aid from the Baseball Assistance Team. He worked in construction and became a minister. He remarried and did a lot of fishing, his lifelong hobby. The Astros inducted him into the team’s Hall of Fame.

In 2015 he wrote a memoir, “Still Throwing Heat,” with Lew Freedman. On the back cover is a photo of Richard smiling in his Astros uniform — the tequila sunrise style, with an orange-shaded rainbow — while casually holding eight baseballs in his right hand.

Johnny Bench, the Hall of Fame catcher, is famous for holding seven at a time. Richard held eight. It sounds impossible, but that is what Richard should represent: the ability to top whatever you can imagine.

His career will always be unfinished. It will never be forgotten.