UK light heavyweight Buatsi made a winning yet underwhelming start to life under recent management with a unanimous decision over Zach Parker in the Manchester arena.
The Olympic medal winner's punch output appeared to earn him a majority decision in a tight ten-round fight at the Co-op Live Arena.
But the challenger landed significant shots, connecting with powerful single shots in a contest where the techniques failed to mesh, with constant grabbing marring the action.
The scoring judges had it 96-94 to Buatsi, with the remaining official a 95-95 draw.
"It wasn't my greatest display but what defines champions? They succeed," the victor commented in the arena as he was met by disapproval from the spectators.
The British fighter returned to winning ways after his maiden career setback - an epic battle with Callum Smith in February - to earn a 20th pro success.
Various analysts thought the challenger, 31, should have been awarded the victory but the Derbyshire fighter suffered the second defeat of his 28-bout career.
Buatsi Secures Victory in Dull Encounter
The fighter's advancement has slowed in recent times through contract problems and long spells of inactivity.
Once tipped as the next star of the British fight scene, he now is positioned trying to achieve expectations - maybe in what seems like a ultimate opportunity - under fresh management.
He started carefully, with neither fighter ready to take risks in a calculated initial rounds.
Parker, whose only previous defeat came at the lower weight class against John Ryder in two years ago after suffering a hand injury mid-fight, was participating in his second bout at light heavyweight.
By the fight's midpoint, the underdog had stayed in contention, creating difficulties for Buatsi, who utilized a solid defense to barely take the cleaner stanzas.
The spectators' acceptance wore thin because of constant clinching, with the challenger falling to the floor multiple occasions during clinches.
The underdog finished the stronger, but multiple periods were hard to judge. Nevertheless, previous titleholder the boxing analyst - providing analysis for Dazn - had it strongly leaning for the challenger, scoring for Buatsi just only one stanza.
Buatsi moves on, but with the caliber of heavy hitter Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - based on this performance - still looks steep.
Ricky Hatton Homage Fuels All-Manchester Battle
In the supporting bout, Arthur defeated Bradley Rea by divided decision in a outstanding local rivalry fight to capture the European light heavyweight title.
The arena fell silent for a deeply poignant tribute ahead of the contest as a bell ceremony tolled in honor of Manchester's own Hatton, who died 46 years old in recently.
It was the first major televised match card in the urban center since the passing of Hatton. As the last bell ended, the quiet gave way to a roar of "there's only one Hatton".
The action during the bout matched the emotion. Arthur was floored by a powerful punch squarely on the jaw in the initial stage, standing uncertainly to his position on the referee's count.
But the traditional red equipment of Arthur soon came forward again. Across the ring, the opponent - in competitive blue - was injured soon, heavy swelling forming under his eye as the duo traded powerful shots.
The challenger, 27, delivered effective strikes but Arthur, thirty-four, fought fire with fire with powerful upward punches as the pace hardly diminished over 12 rounds.
The victor edged the verdict with judges scorecards of 114-114, narrow lead and clearer margin, but each competitor were determined and brave, everything their inspiration the legend represented.
