Frank Deford, shown in 1991, died Sunday at age 78. (Susan Ragan/Associated Press)

Frank Deford practically invented the notion of multimedia: He exported his voice to radio, TV and film, and if you didn’t know him you might have thought he was an actor, because he wore purple suits and looked like Clark Gable. But Frank, who died Sunday at age 78, was a writer above all things, and an important one. His work, most of which appeared in Sports Illustrated, was identified by two qualities that made it important. The first was sincerity, which is a form of truthfulness. The second, and this is not unrelated to the first, was a kind of sweetness. You always came away liking his subjects for their flaws. Not in spite of them. For them.

The funny thing was, Frank didn’t write about people who were easy to like. Jimmy Connors. Bobby Knight. Bill Russell. They defied idolizing. Frank picked them on purpose, I think, because he understood that sports are stories we tell ourselves about who we would like to be — but aren’t. Games are not stories on the level of Hollywood, or best-selling novels; there is a crucial difference: What happens on the field is real, authentic in a way no movie can be, with real people committing real acts. Athletes are ordinary beings with the same flaws as the rest of us, and like all of us, they frequently fail. They fail, they curse, they snarl, and they fail ethics tests, too. They are not the perfect representations of virtue we’d like them to be. This is where all the trouble starts. And that was right where Frank Deford went, and started digging in.

He took on a long profile of Connors when the tennis great was mired in a terrible psychological slump, having lost six of seven majors, and pressed a finger on him: Connors was “swollen with vitriol and tension.” Yet by the time he got done with Connors, you understood him a little, because you’d glimpsed his lurking charm and vulnerability, and how unsparing his mother, Gloria, had been with him, whapping the ball at his head, saying, “You see, Jimbo, you see what even your own mother will do to you on a tennis court?”

He meticulously dismantled Knight’s temper as if he were a bomb disposal expert, picking at his wires with tweezers. Knight was “still a prodigy in search of proportion,” Frank explained. The excesses and the mouth that used “bad language like a weapon” came with an astringent honesty and unrelenting standards. He introduced you to Knight’s father, a man of such old-world strictness that he took out a 20-year mortgage and paid it off in four. Knight was a “substance guy in a style word,” and the juxtaposition was what made him so irascible.

Frank’s work taught the aspiring sportswriters who grew up on him that games are stories about who we really are — and to forget that was to be in danger of drifting into cliche and template and myth, and those weren’t nearly as affecting or moving as the truth. That tension between truth and myth was in all of Frank’s work, but especially in his novel “Everybody’s All-American,” which became a superb film about the graying of an adored football hero into just a man with a gut. Frank was okay with that graying — he found incredible dignity in it. There was a whisper under all of Frank’s work that if we demand too much myth instead of truth, pretty soon we start liking and not liking people for all the wrong reasons.

Who are athletes really, and do they have qualities that are actually worth admiring? He asked that question in every story, and in every one, the answer he arrived at was emphatically yes — just not in way you thought.

To me, the most meaningful and complicated if not the best story Frank ever wrote was about the German heavyweight Max Schmeling. He was an Aryan poster boy for the Nazis, who had enjoyed the attentions of Hitler and admitted he had knowledge of the camps. Yet he had also refused to join the party and tried to aid Jews. Frank’s piece portrayed Schmeling in all his aging complexity, his mixture of pride and sin of omission, expedience in the face of evil, and his tangled sense of moral responsibility. Frank wrote: “Most Americans of a certain age know for an absolute fact that, long ago, Max Schmeling was the dirty rotten Nazi who got lucky and beat Joe Louis, but then got his comeuppance when our good Joe demolished him in the rematch — sticking it to Hitler in the bargain. Schmeling, though, was never a Nazi. He was sometimes credulous and sometimes weak and often an example of what the road to hell is paved with.”

Frank interviewed the widowed old man in his country house eating potato pancakes, and told us about how Schmeling had stood by his Jewish trainer despite threats from Joseph Goebbels, and how during Kristallnacht, Schmeling had hidden two Jewish teenaged boys, Henry and Werner Lewin, for four days and tried to help them to safety. “I was only doing the duty of a man,” Schmeling said. He was only “somewhat” proud of his actions.

“Somewhat,” Frank wrote, pressing that finger of his down again. “. . . It is such an honest, tempered word. It signals to us, more than anything, that you had to have been present when the Third Reich was aborning and then thriving and then crumbling. Then you never would be so sure again. There would always be a somewhat in your life.”

We all have our somewhats, Frank suggested in the piece. An athlete may give his all in the ring, and do a heroic thing out of it, yet also be a half-hearted soldier of the Wehrmacht who had for a time accepted favors from Hitler. Remember that. The heroes and the villains are never simple.

“An honest tempered word.” The phrase equally applied to Frank; that was exactly how he wrote. There is a wonderful line from Schmeling in the story. He says, “I was given a life and I used it.” The same with Frank Deford. He was given a life — and he used it.