After looking through the game logs of every top rookie drafted since Art Heyman was selected at No. 1 out of Duke in 1963 (the year that Basketball-Reference starts displaying game logs), I can safely say that this is unique. No first pick in NBA history has ever gotten off to a start this slow.
In fact, only two names stand out after that copious research.
First, we have Brad Daugherty, who is both the older and less applicable comparison.
Back in 1986-87, the Cleveland Cavaliers big man got off to a
sort-of slow start. He scored eight points in his professional debut against the Washington Bullets, doing so on 3-of-8 shooting from the field. Daugherty's second game was more of a masterpiece, as he dropped 18 points and 15 rebounds on only 15 field-goal attempts. While turnovers were problematic, he was already proving why he was the No. 1 pick.
But then the wheels came off.
Daugherty was 1-of-8 in his third game and stopped getting so heavily involved. Over the next two games, he'd score a total of 15 points on 5-of-12 shooting, which allowed him to finish the opening five-game salvo with a 45.6 true shooting percentage.
Again, not even close to as bad as Bennett's debut, but still not as stellar as we've come to expect from No. 1 picks. There have been worse sets of five-game starts for No. 1 picks, but I'm homing in on Daugherty because he was selected in the midst of a run of great top rookies.
David Robinson and Patrick Ewing sandwich him, and Hakeem Olajuwon was picked at No. 1 just two years prior. Compared to all of them, he stands out in a negative way, even if he'd turn his rookie season around and make a strong second-half run at Rookie of the Year.
The other comparison is a name you've probably heard thrown around as a draft bust countless times: Kwame Brown.