UK light-heavyweight Buatsi made a winning yet disappointing debut to life under recent management with a points victory over Parker in Manchester.
The Olympic medal winner's activity level appeared to earn him a judges' verdict in a close ten-round fight at the Manchester venue.
But the challenger had his moments, connecting with powerful individual punches in a match where the styles failed to mesh, with excessive holding spoiling the contest.
The officials judged it 96-94 in favor to Buatsi, with the final judge a even score.
"It wasn't my greatest performance but how do champions respond? They win," the victor stated in the ringside as he was met by negative reactions from the spectators.
The British fighter bounced back after his first professional defeat - an thrilling contest with his previous opponent in February - to secure a 20th career victory.
Some ringside observers believed the challenger, thirty-one, deserved the win but the British boxer endured the second setback of his 28-bout professional journey.
Buatsi Claims Triumph in Slow Match
Buatsi's progress has plateaued in the past few years through promotional disputes and considerable time of inactivity.
Previously predicted as the future of the British fight scene, he now is positioned trying to fulfil that early promise - perhaps in what seems like a final roll of the dice - under new promotional backing.
He opened tentatively, with the two boxers prepared to take risks in a calculated opening few rounds.
Parker, whose single earlier setback came at super middleweight against John Ryder in two years ago after damaging his hand during the bout, was making just his second appearance at light-heavyweight.
By the halfway stage, the underdog had stayed in contention, making life awkward for the favorite, who utilized a protective stance to edge the cleaner periods.
The spectators' acceptance decreased because of regular grabbing, with the challenger falling to the floor various instances during grappling.
The underdog ended stronger, but multiple periods were difficult to score. Nevertheless, ex-champion Carl Frampton - working with the broadcast network - had it particularly wide for the challenger, awarding Buatsi just one round.
The victor progresses, but with the caliber of hard hitter Benavidez, and Russian champion Dmitry Bivol ruling the division, the road to world glory - based on this performance - still seems difficult.
Hatton Homage Motivates Local Rivalry Battle
In the co-main event, Arthur overcame Bradley Rea by divided decision in a outstanding all-Manchester battle to secure the European light-heavyweight championship.
The stadium grew hushed for a deeply poignant memorial ahead of the contest as 10 bells rang in honor of local hero Ricky Hatton, who succumbed aged 46 in September.
It was the initial significant broadcast boxing event in the location since Hatton's passing. As the last bell disappeared, the quiet transitioned to a roar of "there's only one Ricky Hatton".
The action during the bout reflected the emotion. Arthur was sent to the canvas by a significant blow flush on the chin in the early round, getting up unsteadily to his footing on the referee's count.
But the red-colored attire of the fighter soon pressed ahead again. On the opposite side, the opponent - in rival City blue - was damaged soon, heavy swelling developing under his orbital area as the duo landed powerful shots.
Rea, 27, connected with strong blows but the champion, 34, responded in kind with stinging uppercuts as the intensity seldom decreased over the full distance.
The victor barely secured the result with scoring tallies of even score, close margin and 115-112, but each competitor were persistent and brave, all the qualities their idol the legend stood for.
