Ronald Reagan won by not losing, or so the pundits will probably say today, but Sunday night's second and final presidential debate was touch and go -- Fritz and starts -- much of the time, about the most even match-up since Jimmy Connors last met John McEnroe. Maybe not as exciting but about as even.

However, it was even in negative terms. Both candidates seemed equally lacking in stature.

After the debate, telecast live from the Music Hall in Kansas City, Mo., most network commentators and reporters seemed to think Ronald Reagan had done better than during his previous encounter with Walter Mondale two weeks ago, during which Reagan fumbled and stalled, and that Reagan did not do badly enough Sunday night, nor did Mondale do well enough, to make a seismic impression on the American electorate. Therefore, few minds would be changed and Reagan's lead was safe. The debate did not seem like the beginning of the last two weeks of the campaign; it seemed like the end of the campaign.

It was generally agreed that Reagan had not been all that great a great communicator. ABC's George F. Will found Reagan "measurably sharper" than last time, but NBC senior political correspondent Roger Mudd noted of Reagan, "It is obvious he was not sure of himself this evening. He did tend to wander around occasionally when the questioning got close." Mudd said of Reagan's rambling closing statement, abruptly cut off in mid-piety by moderator Edwin Newman when the clock ran out on the old boy, "I'm not sure what the point of most of that was," and NBC's John Chancellor thought Reagan was "just awful at the end," when he rambled and lost his train of thought.

Four minutes is a long time for Ronald Reagan to ad-lib. As Mondale campaign manager Robert G. Beckel said on Sunday's edition of "This Week With David Brinkley" on ABC, "Ronald Reagan without the script is like Babe Ruth without a bat. He's not going to hit it anywhere." Mondale was not setting the night ablaze either, however. Bill Moyers, CBS News commentator, noted the flimsiness of Mondale's offensive and said, "He kept going for the jugular with a feather."

One thing was clear from the outset: Ronald Reagan was not going to be a Sleepytime Guy during this debate, as he had appeared during the last one. Wound-up, revved-up and propped-up, he burst out of the starting gate with what was for him a rapid-fire response to the first question. He talked so fast he was left with time to fill, so he repeated himself. Reagan had a fairly smooth time until his messy closing statement when there were two long, confused pauses and a pointlessly extended recap of his standard anecdote about writing a letter for a time capsule while driving down Pacific Coast Highway, or some such thing. Reagan had launched into an ode to American youth and said to viewers, "We have met your sons and daughters," when Newman, according to the rules set down by the League of Women Voters, cut him off. The president never got to his shining city on a hill. He was left out there among the grubby suburbs in the Valley.

Reagan was on the defensive much of the time and more than he had to be. "I'm afraid I misspoke," he said early in the debate with regard to a previous statement on the CIA in Nicaragua. "I never ever conceived such a thing; I never said such a thing," he protested to Mondale regarding an alleged Reagan statement that strategic missiles can be called back after being fired. A later sentence on another issue began, "I never suggested . . ." And, "No, I never defended Somoza." Then there was the tiny gaffe of referring to "the policies of weakness of the last four years," suggesting Reagan had flashed back to 1980 and was debating Carter all over again.

A couple more things were clear from this debate: Reagan should never have agreed to debate, and the Democrats should never have chosen Mondale to be their candidate in an age of televisionosis. A young, dynamic, aggressive Gary Hart would have made a stunning visual contrast to Reagan, who even Sunday night looked elderly and befuddled in some shots, but Walter Mondale, with bags under his eyes to rival Fred Allen's, was not enough of an image contrast, to put it mildly.

Reagan took advantage of the so-called age issue to get in a joke. "I am not going to make age an issue in this campaign," he said. "I am not going to exploit for political purposes my opponent's youth and inexperience." Ronnie's second biggest laugh came at the expense of a Mondale commercial that Reagan said featured the candidate talking about defense from the deck of the Nimitz. If Mondale had been in charge, Reagan said, "he would have been deep in the water out there, because when the Nimitz was built, he was against it."

Mondale again chose to look directly into the camera, at the viewer, rather than at the reporter who asked him a question, as Reagan did until the closing statements. Mondale hammered away at America's alleged humiliation in Lebanon from the outset, making at least three references that used the word "humiliated" or "humiliation," then chided the president for Vice President George Bush's claim that Democrats had said Marines in Lebanon died "in shame," which neither Mondale nor running mate Geraldine Ferraro had ever claimed. Reagan sensibly ignored the challenge to apologize on Bush's behalf.

There was an eerie and frightening undercurrent, maybe overcurrent, to the debate. Here were two men, watched by perhaps more than 80 million Americans, talking about "Armageddon" and mass nuclear destruction in awfully casual terms, and in discomfortingly simplistic ones. The unthinkable had become matter-of-factly discussable, even mundane. Reagan was particularly blunt on the operation of land-based missiles: "You put your thumb on a button and somebody blows up 20 minutes later." It did sound like we were all back at Universal making "Hellcats of the Navy." Mondale was not much better, leapfrogging to the right of Reagan on such issues as sharing "Star Wars" anti-missile technology with the Russians. Suddenly he was the hawk and Reagan was the dove. Then he offered a little refrain from one of his terrible TV commercials, about how computers could start World War III, except that once he started to say that "commuters" could start it. And perhaps they could. Why, there are times on I-95 -- but that's another debate.

As Johnny Carson joked after the first presidential clash, now Ronald Reagan had everything: He was ahead in the polls and he was the underdog besides. Reagan's performance Sunday night was hardly spectacular, except as an improvement on his last debate appearance, but it wasn't terrible enough to make a dramatic and decisive television impression. And he looked good. He loomed larger than Mondale, even in shots in which Mondale was in the foreground and Reagan in the background. He exuded a kind of belovedness. He didn't seem to know much more about foreign policy than the Average Joe, and that is apparently one of the things Average Joe likes about him. Average Joe doesn't care about Helsinki Accords and the Pacific Basin and stealth bombers, it would seem, as long as the president of the United States is nice. This is the Nice Age.

The questioners this time were not as good as at the first debate. In 90 minutes on foreign policy, none of the four reporters brought up the recent Chernenko initiatives and the White House's chilly response to them. Newman cautioned reporters to keep their questions brief, but every question asked by reporter Georgie Anne Geyer was a speech. It was a white paper. She was arduous and awful.

Much has been said and written about whether such debates have value and whether they merely test superficial and irrelevant capacities of the participants. But if the exchange Sunday night was not always particularly illuminating, it was absorbing throughout, and it did deal, however clumsily, with the life-or-death issue of our time. "This debate means nothing," ABC's Will declared on the Brinkley show, yet there he was busily analyzing it Sunday night with his colleagues. It didn't mean nothing, it meant something. Among other things, for Walter Mondale, it probably meant certain defeat, even though his makeup did give his face a chipper, peachy glow. The trouble is, bags under eyes don't look that great even when they're peachy. When he looked into the camera and implored, "Vote for Walter Mondale," he sounded like he was running for president of the senior class. And losing.