The loss was the worst in Roos' career – his previous highest was 73 points – and the former Sydney coach couldn't believe the number of fundamental errors made.
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"If you get hold of the ball and you fumble it all the time, if you can't make tackles, they're the most basic things in footy. Today we were just really poor at it," Roos told reporters.
"Whether that's habits, but certainly it's been going for a long time, I suspect. How do you break the habits? You've got to keep training for it and training for it or you just pick different blokes.
"It's round two, but I'm certainly putting a dossier together," he added.
"It's early in my tenure here, but certainly you're building up a profile on each of the players, you're seeing them under the heat, and you're seeing what they can and can't do.
"There's some non-negotiables in footy. That's just the reality of what the game is.
"If you can't do them, you can't play."
In an odd occurrence for a 93-point loss, Melbourne equalled West Coast in the statistics, the Demons recording 391 disposals to 385.
The problem was that many of these disposals were either backwards or sideways and often took far too long, allowing West Coast to waltz back into a defensive position.
And, when the Dees invariably turned it over, the Eagles would generally only need two or three possessions to make them pay big time.
Roos conceded that not having a forward line – Mitch Clark is on personal leave while Chris Dawes and Jesse Hogan are injured – was hurting his side's forward movement. But the coach wasn't in any mood for excuses.
"Some of the stuff today … guys missing chest marks," he said, one of which was in reference to a poor Jack Watts' missed mark that was rapidly transferred down the other end for an Eagles' goal.
"I haven't seen that before, so it's an eye-opener for me.
"Some of the errors were just incredible. At some point you've to draw a line in the sand and say 'These are the guys we're going to pick'."