For the second time this season, he had just witnessed an opposition player kick a match-winning goal inside the last minute of the game.
In round 15 it was West Coast's Josh Kennedy; on Sunday afternoon it was Port Adelaide's Chad Wingard.
Wingard's fifth and the game's final goal was the Power's fourth in a row to finish the game, turning a 20-point deficit at the 22-minute mark into a four-point victory.
Jacobs was almost lost for words.
"Being South Australian, I love playing in Showdowns and [the loss] absolutely guts me," Jacobs said.
"Sitting here, there's still a bit of shock because the position we're in ... it's definitely one of the toughest losses I've had."
Coach Brenton Sanderson conceded the loss had finally ended his side's finals tilt.
Adelaide now sits four wins and percentage behind the eighth-placed Power with just four games remaining.
Sanderson lamented "brain fades" and "silly errors" that he admitted were starting to become habit for his Crows.
"We shouldn't have lost that game. Twenty points up with five minutes to go or six minutes to go, it seems to become a habit now [when] we make some silly errors when we shouldn't," Sanderson said.
"We didn't kick straight last week against Fremantle, we beat Geelong, we were 13 points up against West Coast with two and a half minutes to go and lose the game, so we've got to work out why we have these little brain fades.
"It's happening too many times … I don't want to ever see (it) again."
The narrow loss was made possible, in part, by an incredible bounce that saw Angus Monfries' attempt on goal roll through.
With the Power down by eight points, Monfries' left-foot shot from 49 metres looked like skidding through for a behind before bouncing at right angles through for a major.
It's as if Sanderson spent the summer walking under ladders.
"Monfries' bounce was a nice little right-hand turn, if that goes through for a point, maybe we win the game," he said.
But luck played only a small role in Adelaide's loss. While the Power were lucky with Monfries' goal, the Crows also suffered good fortune when Matthew Broadbent turned the ball over to Matthew Wright deep in Port's defence for a simple goal earlier in the term.
Harry Thring is a reporter for AFL Media. Follow him on Twitter: @AFL_Harry
