Although an allergy brought on by a rare day on the golf course was a nuisance at lunch, it wasn't Gene Shue's main cause of concern.

The Washington Bullets' coach, although he has spent 15 years directing National Basketball Association teams, can recall only one other time when he approached a season with so much anxiety and uncertainty.

When he called a meeting at 4:30 yesterday afternoon to brief his new players on the two-a-day practice sessions that will begin this morning, never have so many mystery guests showed up.

Low draft choices, free agents, castoffs and rejects made up the contingent. Yet, the way things appear now, some of them could be wearing Bullet uniforms when the team's regular season opens Oct. 30 in Boston.

"The only thing I can compare this to is my first year at Philadelphia," Shue said. "The Sixers had won only nine games the year before (1972-73). They had some veterans, but I knew we had to make wholesale changes, overhaul the whole team.

"This year may not be quite as drastic, but it's right up there. It's very unusual to lose so many established players all at once."

While many NBA teams will open practice next week with one position or opening to fill, the Bullets must rebuild their entire front line. With Wes Unseld now serving the club in an administrative capacity, Elvin Hayes enjoying a homecoming in Houston and Mitch Kupchak moving to Los Angeles, Shue is wondering where his first rebound is coming from.

"Rebounding is my No. 1 concern," the coach said. "In the past, with Wes and Elvin, this was something the Bullets never had to think about.

"Now we don't have those specialists anymore. The emphasis this year is going to have to be on doing everything as a team. Instead of everybody knowing that two guys would take care of most of the rebounding, now we need help from everybody."

Jim Chones, the 6-foot-11, 220-pound acquisition from Los Angeles and the Bullets' most experienced rebounder, isn't being counted on to carry the load.

"Going into the season, I'm thinking of Jim as more of a swing player," Shue said. "He's been a good player, he's been effective with Cleveland and Los Angeles. I've watched him for a long time and I know his strengths and weaknesses. He's the type who can come in and help us at either center or power forward."

Shue's first big move has been to shift Greg Ballard to Hayes' spot at power forward, but that means additional rebounding will have to be gotten from the quick-side forward.

"Small forward is wide open," Shue said, with a sigh. "The major problem is that he must be a rebounder. We're going to have to get more help on the boards from that spot."

With rebounding ability the first criterion at that spot, that apparently eliminates Don Collins, the 6-6 swing man obtained from Atlanta in a 1980-81 midseason trade for Wes Matthews. Collins has the quickness and the ability to drive to the basket that Shue likes, but he's not a rebounder.

Collins may have the big guard spot to himself if the Bullets don't match Indiana's offer sheet for Kevin Grevey, and they don't seem to be in any hurry to do so.

"Our intention still is to sign Kevin unless some team gives us a good offer," Shue insisted. "We'll be listening to everybody this week and then make a decision.

"I'd like to have a guard who can rebound," the coach continued. "Teams like Los Angeles with Magic (Johnson) and New York (with Michael Ray Richardson) get a big boost in their running game because they have guards who can get the ball off the boards and start the break. The Bullets always had enough rebounding from Wes and Elvin and never had to think about help from the guards before."

Rebounding, of course, starts with the center and presently Rick Mahorn is slated to replace Unseld. The 6-10, second-year pro from Hampton Institute was used sparingly last season and is an unknown quantity.

"Rick did quite well this summer," Shue said. "He made a major improvement over last season, but he's still a very big question mark."

In addition to Chones, the other candidate for the pivot position is Jeff Ruland, who played in Spain last year. Shue says Ruland is a raw rookie with a great deal to learn.

"You can go up and down the whole front line and it's one question mark after the other," Shue said. "That's why we're starting camp so early. We've got a lot of work to do."