Some of the key stats showed the Magpies were in control but they couldn't counter Port's youthful enthusiasm as last year's 14th-placed side surged into next weekend's semi-final with Geelong, leaving Collingwood to lick their wounds over post-season drinks.
A shocked Maxwell accused his side of butchering the ball.
"In the end it's just a feeling of shock. We don't even feel disappointed yet," Maxwell told reporters in a very quiet Collingwood change room.
"We won clearances by a mile, contested possessions, inside-50s by a mile and we lost the game.
"You don't come to an elimination final expecting to be in this position.
"Steele (Sidebottom) was kicking for an eight-point lead halfway through that (final) quarter and he missed and in the end they just over-ran us.
"It wasn't the last 15 minutes that killed us. It was the first 100 when we didn't use the ball well enough and we wasted opportunities going forward.
"Unfortunately we just butchered the ball.
"We've got to sit back and watch the next three weeks so (it's) definitely a failed season."
It's the first time since 2006 that Collingwood, plagued by injuries this season, haven't reached the second week of the finals.
Maxwell said Josh Thomas, Marley Williams, Ben Sinclair and Lachie Keeffe were developing well along with small forward Jamie Elliott.
However question marks remain over the playing futures of veterans such as small forwards Alan Didak and Andrew Krakouer.
"I've got no idea what the status of all those guys are," Maxwell said.
"I've signed a one-year deal so that's where I sit," added Maxwell, 30.
The 2010 premiership captain said the Magpies had gone into this season shooting for a flag.
"For the last five years we've gone in expecting to be a premiership contender," he said.