George Allen had just finished his daily briefing for the press the other day and was walking back to his dressing room when another brilliant though clicked in his head.

"Somewhere out on that football field." he said, turning back to the reporters, "there's a new guy who's going to make some big plays for us this year. I don't know who he is yet, but that's something we've got to find out. He's out here, I know that. Now it's just a matter of making the right choice."

At the moment, there are several candidates for the role of Allen's sleeper of the year. Maybe it will be Reggie Haynes, the rookie tight end with great body and the super speed. Perhaps it will be Joe Harris, a veteran linebacker from the Canadian league who keeps drilling folks in practice.

And then there is the raw-boned redheaded kid with the size-15 sneakers and a knack for being in the right place at just the right moment. His name is Mark Murphy, and the Red-skins believe this free-agent safety from Colgate may be the man Allen is looking for.

"He's still got a long way to go and a hell of a lot to learn," said secondary coach Ralph Hawkins. He has good scene, intelligence and ability, and he never stops hustling. But the key will be the stops hustling. But the key will be the special teams. If he shows he can contribute there - and I think he will - then he's got a shot."

Already Murphy has demonstrated an instinctfor being around the football. He intercepted passes in two of the Redskins' three rookie scrimmages, and also impressed the coaching staff with his fearless and pad-popping tackling style.

Allen keeps calling Murphy his 13th -round draft choice. After the regular 12-round draft was completed last spring. Murphy was the first collegiate player the Redskins signed.

hey ever went so far as to fly him to Washington before the draft, with the promises that they would pay for his plane ticket if another club selected him Murphy says now that "not being drafted may have been the best thing that happened to me.

"Initially, I was kind of disappointed," he said, "but it allowed me to pick and choose and it helped me get a little better bonus. I was contacted by Kanssas City and Giants, Denver and Buffalo, but the Redskins were the only team with a winning record that was interested. I just figured I'd like to play for a winning team, so I took a chance on coming here."

It was a very big chance, mostly because the Redskins are chock full of talented defensive backs. Murphy has been used at free safety, the same position all-pro Jake Scott has a stranglehold on.

Veteran Brig Owenscan play both safety spots and the corner, and Eddie Brown is going to be around returning punts and kickoffs and backing up both Scott and strong safety Ken Houston.

The Redskins kept only seven defensive backs a year ago, and Murphy at the moment would seem to be the odd man out. "But you never know in this game," said Hawkins. "With six exhibition games, well, a lot of things can happen."

Hawkins saysMurphy reminds him of two other big-play defensive backs once on the Redskins' roster - Jon Jasqua, now retired because of injury, and Ken Stone, a starting safety for Tampa Bay after the Redskins chose not to protect him in the 1976 expansion draft.

Both Jaqua and Stone were also known for their affinity for the spectacular play - blockedpunts, field goals and interceptions. "If he could be half as good as those guys on the special teams, that's all you could as for," said Hawkins. "I think as far as playing in the secondary alone, he probably has more abilitythan those guys."

"Sure he's borderline on some things. If he wasn't he would have been drafted. But that's not always a good criteria. A lot of fine football players in this league were never drafted, and we think this kid is going to be a fine football player."

Murphy was all of that and more for Colgate, a four-year starter in football and baseball. He also had several offers to play major league baseball out of high school in Buffalo, "but I wanted to go to college and I didn't like the idea that you could make the majors.

"At least in football, you either make it or you don't and you go on to another career. I've had several job offers, and I'd like to go back to school. If I don't make it in football this year, I can't imagine myself trying again.

"But you can't think about things like that. It's hard to tell how you are doing or what the coaches are thinking. I just try improve everyday. I've been pleased, and I feel a little more confident. I just hope I'll be here when it counts."