Defensive end Dexter Manley of the Washington Redskins seems proud that not only is Mr. D dead, but, "He's buried in RFK Stadium."

"Where?" Manley said, repeating the question at hand yesterday. "Who knows where?"

This is where the jokes stop. Manley had a career-high 13 1/2 quarterback sacks this season and, were it not for a midseason ankle injury that cost him most of two games, he likely would have had more.

The Redskins figure the reason for Manley's increased production is simple: maturity. His whim has become his wham!

"Dexter's settled down. He's over the young years," Coach Joe Gibbs said. "I think he's had a darn good year."

General Manager Bobby Beathard was even more concise with his explanation: "Marriage. Dexter's got a great wife now and the thing I've noticed is his maturity. You see it everywhere. He used to spend a lot of time pouting. Now, if you were to put his emotions and his level of play on a chart, instead of going way up and down, it would be a steady line."

Of course, the line wouldn't be entirely straight and Manley, 25 and in his fourth season, knows this. He still has been fighting pass-rushing inconsistencies.

Chart Manley's zigzag line of '84 this way: he had a career high of three sacks against Detroit on Nov. 11 and in six other games he had none.

"I feel like I can be the best, but I'm slipping and sliding," Manley said. "I want to be a complete player. In all sincerity, I think I could get 20 sacks in a season. But it's like one day I'll have a great game and then I'll go two or three weeks without a sack.

"I think I've had a good year, good enough to go to the Pro Bowl. Yeah, it bothers me that I didn't make it," Manley said.

"No, I didn't accomplish all of my goals this year. I wanted to get 21 sacks, but I got hurt and that had a lot to do with me not getting that many. I still can't cut on my ankle. I remember one play in our game at St. Louis (a 26-24 Redskins loss). They ran at me and made me look bad. I had no mobility."

Manley was married on Sept. 1, the day before the season opener.

"My wife Glinda has helped me a lot," Manley said. "I guess I have matured."

Take out the scrapbook of Manley's tumultuous 1983 and these are the news items: He had a contract hassle in training camp ("They are paying me pennies," he said before signing a renegotiated deal). He arrived at camp wearing a mohawk haircut and subsequently inherited the nickname "Mr. D."

A Texas newspaper once quoted him as referring to Dallas' Tom Landry as something less kind than "Coach." He often was replaced on running downs by then-rookie Charles Mann and finished the season with 11 sacks.

Most troublesome of all, Manley said late last year that he might not mind a trade. The fact is, the Redskins tested Manley's value in the trade market last offseason.

"Before this season started, I did a lot of thinking about my future," Manley said. "I felt it was best for me to be in a good frame of mind. The only thing I wanted to do was what I do best: play football."

So, to begin with, Manley stopped talking with most of the media. "A lot of times in the past," he said, "I know I haven't said the right things."

His silence held until two weeks ago. Yesterday, he sat on a bench at Redskin Park and explained his reticence.

"I made up my mind before training camp that I wasn't going to talk until after the Pro Bowl ballots were done with. At that particular time, I was more concerned about Dexter. The talk about me being traded didn't affect me because I had said that I wanted to be traded late last year.

"I wasn't happy at that time. I wasn't really making the plays. My performance dropped. A lot of times (offenses) put an extra man, a tight end, on me. I wasn't concentrating."

He realizes he made his name in the Redskins' 31-17 victory over Dallas in the conference title game two seasons ago. Manley said he's certain people remember him more for his knockout hit on quarterback Danny White than for deflecting a pass by reserve Gary Hogeboom that was intercepted and returned 10 yards for a victory-assuring touchdown by tackle Darryl Grant.

"I kind of resent the fact that people still think of me mostly for that play," Manley said. "I've been sacking quarterbacks for years. I mean, I had six in my rookie year (1981). It just goes to show you that you have got to knock somebody out to get any recognition."

On the one hand, Manley's stock should be high considering he has 37 sacks in the 56 regular-season games of his Redskins career. On the other hand, because he is so quick with his 6-foot-3, 250-pound frame, there is always the question why Manley doesn't get more sacks and stop more running backs.

"I have never played bad for this organization," Manley said.

Somehow, he always is able to tickle the Redskin funnybone, even in this transition season of his. Like the time he announced in the locker room, "The three most famous people in this country are Michael Jackson, Prince and me."

Or, last week, when he wore dark, Blues Brothers-style sunglasses during noncontact drills. He said he wore the glasses to add comic relief, which he got when he tripped over a dummy bag.

Two seasons ago, Manley predicted he would be the most valuable player of the Super Bowl. He makes no such predictions for Sunday's division playoff game against Chicago at 12:30 p.m. Sunday in RFK Stadium. "I just want to finish strong and be a guy who does his part to get us to the Super Bowl," Manley said.

And no predictions of doom for Bears quarterback Steve Fuller? "Naaw," Manley said. "I've toned down a bit."

For the first time in two years, Gibbs closed practice to every member of the media yesterday.