UK light heavyweight Buatsi made a winning yet disappointing beginning to his career under recent management with a decision win over Parker in the Manchester arena.
The Olympic medal winner's work rate seemingly secured him a split decision in a competitive 10-round bout at the boxing arena.
But Parker found success, delivering effective clean blows in a fight where the techniques didn't complement each other, with constant grabbing spoiling the action.
The scoring judges had it 96-94 for to the winner, with the final judge a 95-95 draw.
"It wasn't my best performance but what do champions do? They succeed," Buatsi stated in the ringside as he was met by disapproval from the audience.
The British fighter returned to winning ways after his maiden career setback - an epic battle with his previous opponent in last winter - to secure a twentieth professional win.
Some ringside observers thought the challenger, 31, merited the decision but the British boxer experienced the second defeat of his 28-bout career.
The Champion Secures Triumph in Slow Encounter
His career development has slowed in recent times through promotional disputes and considerable time of inactivity.
Previously predicted as the future of the British fight scene, he now stands trying to fulfil that early promise - possibly in what seems like a last chance - under new promotional backing.
He started carefully, with both competitors ready to be aggressive in a tentative opening few rounds.
The challenger, whose single earlier setback came at the lower weight class against his former opponent in two years ago after breaking his hand during the bout, was making just his second bout at light-heavyweight.
By the middle rounds, the underdog had made it competitive, causing problems for the favorite, who utilized a protective stance to barely take the better stanzas.
The audience's tolerance diminished amid regular grabbing, with the challenger falling to the floor several times during grappling.
Parker finished the stronger, but several stanzas were difficult to score. Nevertheless, ex-champion Carl Frampton - working with the broadcast network - had it significantly in favor for Parker, scoring for Buatsi just one round.
Buatsi moves on, but with the likes of power puncher Benavidez, and Eastern European fighter Bivol ruling the division, the journey to titles - judging by this showing - still seems difficult.
Ricky Hatton Tribute Motivates Manchester Derby Fight
In the supporting bout, Arthur beat Bradley Rea by close verdict in a terrific Manchester vs Manchester contest to win the European light heavyweight title.
The arena grew hushed for a extremely emotional memorial before the fight as ten bells rang in memory of Manchester's own Hatton, who succumbed aged 46 in last month.
It was the premier televised boxing event in the location since the passing of Hatton. As the final chime faded, the quiet gave way to a shout of "only one Hatton".
The fighting inside the ropes reflected the emotion. The eventual winner was sent to the canvas by a left hook directly to the chin in the initial stage, rising shakily to his position on the count of eight.
But the red-colored attire of the fighter soon advanced again. On the opposite side, the opponent - in competitive blue - was injured quickly, heavy swelling appearing under his orbital area as the duo landed powerful shots.
The challenger, twenty-seven, delivered effective strikes but Arthur, 34, matched the intensity with stinging uppercuts as the intensity rarely dropped over twelve rounds.
Arthur edged the verdict with official scores of draw, narrow lead and wider gap, but each competitor were relentless and brave, all the qualities their hero the legend stood for.
