It would be nice if things were simple in the Washington Redskins' backfield. One quarterback. One running back. All the time.

Not this year.

The Redskins are playing the Denver Broncos in the Super Bowl today and they got to San Diego using a backfield of change. At times it has been George Rogers lining up behind whoever was at quarterback. At times Timmy Smith. At times Kelvin Bryant.

"Basically," said Smith, "It all boils down to who's hot and who's not."

Certainly there is some substitution pattern. Rogers starts. Smith relieves. Bryant's forte is receiving, so he's usually in the game in passing situations, especially on third down. But it doesn't constitute a system.

"No, it really isn't," said Don Breaux, the Redskins' running backs coach. "We've told George and we've told Timmy that we need them both. We will use them as we've utilized them in the last two games. Tim's production has been up, so we'll continue to play him. Yet we need George and we hope we can get Kelvin the ball more from a running standpoint. Giving him the ball on the ground is still a viable option."

Smith has been the latest addition to the rotation. The 5-foot-11, 216-pound rookie has done most of his running in the Redskins' two playoff victories, which might seem a bit odd on the surface.

"Timmy hadn't played a lot in college {because of injuries in his final two seasons at Texas Tech}," Breaux said. "So from the first game through the middle of the year, he had to work really hard running our opponents' plays in practice. It helped him later in the year because they banged him around pretty good."

Smith had earned a spot on the team with 234 yards on 69 carries in the four preseason games. In the eighth week of the season, Smith carried seven times for 54 yards in the Redskins' victory at Buffalo. Then in the second-to-last game of the season, against Miami, Smith carried 11 times for 46 yards as the Redskins gained 204 yards in their second-most-productive rushing day of the year, though it was against a weak Dolphins defense.

Smith got just three carries for four yards in the season finale against Minnesota, but he is the team's leading rusher in the playoffs. Smith gained 66 yards on 16 carries against the Bears and 72 yards on 13 carries against the Vikings. After the Miami game, Gibbs said Smith would come in on the third series, with Rogers working the first two. But with Smith performing well in the last two games, the substitution pattern is even less structured.

"Oh, he's going to play right away," said Breaux, with the look of someone who has stumbled onto a good thing. "We'll alternate them and get a sense of who is hot. We'll start George and Tim will come in right away. Then we'll see how they're doing."

During the regular season, Bryant carried the ball 77 times for 406 yards, the second-highest yardage total behind Rogers' 613. Bryant also gained 490 yards by catching 43 passes, the second-highest reception total behind Gary Clark's 56.

"During the season, sometimes it was good and sometimes not so good," Bryant said of the rotation. "I think it's working good now. We're always fresh and all three can get the job done."

Gibbs said he wanted to get the ball in Bryant's hands 14 or 15 times a game. "I think I can handle that," Bryant said. "That's not a whole lot of times when you compare it to other running backs in the NFL."

Of the three, Bryant is the fastest. Rogers would seem to be the strongest. Smith is a mix.

"I don't think it makes much of a difference," quarterback Doug Williams said. "We can rotate three running backs and still be successful. The bottom line, though, is that the offensive line has to come off the ball. That's the key, no matter who is in the backfield.

"Tim does certain things George can't do. George does certain things Tim can't do. And Kelvin can do certain things both of the others can't do."

Said Smith, "Kelvin is a lot quicker than me and George and a lot faster than me and George. George is very strong. I'm not as strong as he is. But I've got a little quicker feet than George."

Rogers carried 12 times for 46 yards in the NFC championship game.

"I thought I played pretty well, but they still wanted Timmy to play," Rogers said. "But that's just as well because he's playing well, too. It's working out for the best, I guess."

Rogers has always maintained he feels most comfortable when he gets 25 or 30 carries in a game. But with injuries to his big toe, shoulder and groin, and the players strike, Rogers carried the ball fewer times (163) this season than any in his career, except for the strike-shortened 1982 season. With Bryant coming in for passing situations, Rogers lost some carries. Now with Smith working in, it can mean even fewer.

"The main thing is we're winning," Rogers said. "It may be frustrating. This whole season hasn't gone well for some people. I'm sure Jay {Schroeder} would like to be starting. But I want the ball more. Timmy wants the ball more. Kelvin wants the ball more. But with the way we're winning, you've just got to accept it. Hopefully, next year it will be a little better."

Who would get the call if the Redskins were one yard from a winning touchdown and only time enough to run one play?

"Would I get it?" Rogers said, repeating the question. "Wooeee . . . the way our short yardage has been going . . . I think we'd try to run it in. Oh yeah, I'd get it. On the 1, right? Oh yeah, I'd get it."

But on this Redskins team, you just never know.