The Power backed Motlop to respond to his disappointing display against Hawthorn in round 11 with a big game against the Swans, but he failed to deliver again on Saturday night.
After giving away multiple 50m penalties for verbally abusing umpire Matthew Mollison in the third quarter, Motlop dragged himself from the ground.
Motlop also displayed poor body language when young teammates Cameron Hitchcock and Matthew Lobbe both opted to take shots at goal instead of dishing handballs to him.
Motlop has endured a nightmare season both on and off the field in 2010.
He has missed four games through injury and another through a club-imposed suspension, after breaking team rules by picking up his girlfriend from the Darwin airport in the early hours on the day of Port Adelaide’s game against Melbourne at TIO Stadium.
He also stands accused of verbally assaulting vice-captain Jacob Surjan’s girlfriend at a Glenelg bar two months ago.
Cassisi said the leadership group had met with the coaching staff to discuss the issue and that both parties were of the opinion that Motlop needed their support.
“First and foremost we’ve got to support Motts through the weekend and the other issues that he’s had," Cassisi said on Tuesday. "He’s really disappointed about the 50m-penalties that he gave away a few times on the weekend, as much as we were and he understands it’s important at the age he is and with such a young group that he takes a bit more responsibility.
“We need to judge them (players) harshly at certain times and we do that, but at the same time we need to support them.
"We support Motts in trying to turn his form around and be a really good contributor for our side because when he is playing well he’s a very important player for us.”
Port Adelaide dropped to 12th on the AFL ladder after the club’s 38-point loss to the Swans and desperately needs a win against North Melbourne this weekend to keep touch with the top eight.
Injured players Brett Ebert (ankle), Surjan (knee), Jackson Trengove (hip), Hamish Hartlett (quad) and Steven Salopek (shoulder) were all restricted to light duties at training on Tuesday, while Chad Cornes is recovering from concussion.
Robbie Gray (hamstring) was also limited to handball drills, but could be a chance to return against the Roos.
Cassisi said it was important his side snapped its losing streak to keep its finals hopes alive.
“We’re not in a good position at the moment," he said. "We’ve got a few injuries and we’ve lost five games in a row, but I think our supporters need to see us sticking together and working hard to try and get as a result.
“I don’t think our effort could be questioned for the better part of this year.
"Our tackles are up and our contested possessions are up, but we’ve almost gone too much that way.
"We need to get a bit more uncontested footy and get the ball inside 50 more often. We’ve missed important goals at important times and our skills have lacked a bit of polish, so I think that’s what we need to work on.”
