* Of rookies and second-year players who are not probable all-stars, here are the five in each conference who have had the greatest impact on their teams:

East: Roy Hinson, Cleveland; Charles Barkley, Philadelphia; Kevin Willis, Atlanta; Jeff Malone, Washington; Glenn Rivers, Atlanta.

West: Rodney McCray, Houston; Clyde Drexler, Portland; Otis Thorpe, Kansas City; Jay Humphries, Phoenix; Smith, Clippers.

Two rookies of note, Jordan and Sam Perkins, both from the University of North Carolina, are missing from the above list. Both members of the U.S. Olympic team deserve to be on it but for different reasons. Jordan, who is averaging 26.6 points, six rebounds and five assists a game, has had a profound impact, in Chicago but even more throughout the league. Perkins, on the other hand, has struggled with the Dallas Mavericks. Overmatched at center, Perkins' playing time at forward is reduced because of the play of Aguirre and Vincent. Perkins, the No. 4 pick in last June's NBA draft, is averaging only nine points and six rebounds.

If Jordan rates as the individual surprise of the season and Perkins the flop, which teams fit the bill in the above categories? The choice for the most disappointing team of the season so far is simple: the Portland Trail Blazers, who drafted Sam Bowie over Jordan and have an 18-24 record.

While giving Houston and Denver a nod, the most pleasantly surprising team has to be Milwaukee. Picked by most experts to finish between second and fourth in the Central Division, the Bucks have opened a three-game lead on Detroit, the consensus preseason choice.

Grouping the teams league-wide, based on expectations, circumstances and reality:

Head of the Class: Boston, Philadelphia, Milwaukee.

Trying Hard: Lakers, Washington, Detroit, Denver, Dallas, Houston.

Treading Water: Phoenix, New Jersey, Chicago, San Antonio.

Disappointing: Atlanta, Clippers, Seattle, Portland.

Lottery Time: New York, Indiana, Cleveland, Utah, Kansas City, Golden State.