Tom McMillen got up at 7 yesterday morning and ran four miles.

"That should answer any questions about how serious I am about helping the Bullets," he said at a Capital Centre news conference yesterday announcing his acquisition by Washington.

"I'm ecstatic about coming back to my home to play," said McMillen, a three-time all-America at the University of Maryland and a resident of Crofton, Md. "I've been battling them for years and now I'm delighted to be on their side."

Bernie Bickerstaff, the Bullets' assistant coach, said he expects McMillen to play 15-20 minutes a game in relief of Jeff Ruland and Rick Mahorn.

"We've been trying to get him for two years," Bickerstaff said. "One of the deciding things was that whenever we played Atlanta we spent a lot of time in the locker room trying to think of ways to minimize his effectiveness. His innate intelligence, shooting and passing ability will really help our front line."

McMillen, who is 6 feet 11, said he played all three front court positions with the Hawks.

He said he was surprised when he heard of the trade, but that he knew Atlanta was initiating a youth movement, "and will be doing some experimenting. I'm glad to be coming to a team with so much stability," he said.

It took quite a bit of maneuvering to get McMillen. The Hawks had the right to exercise an option year on McMillen's contract, which had expired at the end of this past season. But before he could be traded, the Hawks had to exercise the option and then make the deal.

It was agreed on, in principle, before the June 28 draft, but wasn't settled until Tuesday, after McMillen returned from London where he had attended a Rhodes Scholar reunion.

The Hawks told the Bullets the player they wanted for McMillen was Indiana guard/forward Randy Wittman, so the Bullets drafted him and then traded his rights to the Hawks for McMillen and a second-round draft choice next year.

McMillen is under contract to the Bullets for one season. He has been active politically and has indicated he might seek office as early as 1984, but is uncertain if basketball will prohibit that.

"I said a long time ago I'd play until two things happened--I wasn't contributing or I wasn't having fun. I'll have to see how this year goes."