The Bahamian was suspended without pay Oct. 24 after testing positive for a diuretic. His ban began the following night against the Denver Nuggets and concluded after Monday's loss to the Portland Trail Blazers.
When the suspension was announced, ESPN reported the NBPA was preparing to file an arbitration case on behalf of Ayton under the CBA provision of "unintentional ingestion." If successful, his penalty would have either been rescinded or reduced.
The 21-year-old wound up serving the entirety of the ban.
"I was just really shocked and embarrassed, but most of all, I know I disappointed everybody that's in my circle," Ayton said in an interview Wednesday.
Last week, head coach Monty Williams all but officially confirmed his plan to reinsert Ayton into the starting lineup. Williams told Forbes Sports' Brendon Kleen, "I feel like DA can come right back in and be a starter and everybody will be just fine."
Ayton looked promising in his 2019-20 debut, registering 18 points, 11 rebounds, and four blocks in a 29-point win over the Sacramento Kings in the season opener. The big man was permitted to practice with the Suns throughout his suspension.
"He's got a lot of frustration and energy pent up that I know he's ready to let go," said center Frank Kaminsky, according to the Arizona Republic's Duane Rankin.
Kaminsky and Aron Baynes filled in at center throughout Ayton's absence, during which the Suns went 10-14.
Ayton averaged 16.3 points, 10.3 rebounds, 1.8 assists, 0.9 steals, and 0.9 blocks last season as a rookie after being taken first overall by the Suns in the 2018 draft.