The Exchange
Basketball-Reference's Phoenix, Seattle and league transaction logs all place the deal on June 4, 1980: Phoenix sent Paul Westphal to Seattle and received Dennis Johnson. The date correction is important because the legacy archive record carried June 3. Both players arrived with major credentials. Westphal had just averaged 21.9 points for Phoenix and made the 1980 All-NBA First Team, while Johnson was coming off a 19.0-point season for Seattle with All-NBA Second Team and All-Defensive First Team honors.
Phoenix Return
Johnson immediately supplied the stronger sustained return. In 1980-81 he played 79 games, averaged 18.8 points, made the All-Star team, earned All-NBA First Team and All-Defensive First Team honors, and helped Phoenix win the Pacific Division. He followed with 80 games, 19.5 points per game, another All-Star appearance and another All-Defensive First Team selection in 1981-82. In 1982-83 he played 77 games, started 74, averaged 14.2 points and 5.0 assists, and again made All-Defensive First Team. That is three seasons of high-level two-way guard play directly realized by Phoenix. Johnson's later championships with Boston confirm his longevity, but they are not credited as Suns value in this transaction.
Seattle Return
Westphal was still a real player, so Seattle did not receive an empty return. He averaged 16.7 points and 4.1 assists in 36 games and was selected as an All-Star in 1980-81. The problem was availability. Basketball-Reference shows only 36 appearances, and contemporary transaction research plus UPI reporting document a right-foot problem that repeatedly removed him from the lineup. He did not play another regular-season game for Seattle after that season. That makes the Sonics return meaningful but brief: one productive partial season from a decorated guard rather than multiple years of dependable top-end play.
Final Verdict
The direct club value favors Phoenix by a wide margin. Johnson gave the Suns 236 regular-season games across three seasons and remained an elite defender throughout that run; Westphal gave Seattle 36 games in one injury-disrupted season. Phoenix receives an A- for converting an outgoing star into a younger guard who immediately produced All-NBA and repeated All-Defensive value. Seattle receives a C- because Westphal still produced at an All-Star level when available, preventing the return from being treated as a total loss. The final verdict is Phoenix Suns Win, based on realized value with later Boston accomplishments excluded from Phoenix's grade.