Extrapolating from last week's match-ups this this weeks is a fool's errand. Kennedy and Buddy are completely different beasts. Buddy is big, but doesn't play tall. When was the last time he took a pack mark, or even a mark over his head? Collins has some good attributes, but leg speed isn't one of them. That makes him little limited, and certainly he would have been an appalling match-up for Buddy.
Kennedy is more versatile. He can get out on the lead, crash a pack and take a good pluck overhead. You'd give Collins a crack on the basis he can match him in the air, and hope that his teammates can cover the space in front to head off any leads. But that didn't work out, and that's not all Collins' fault. Dawson has a good record against Kennedy, but I don't think he'd have fared much better today (although he would have worn a great deal more scorn).
It was a good learning experience for Collins, but the secondary point is where would Collins have gone had he been moved off Kennedy? West Coast were playing a pretty small forward line with only really Darling, Le Crap, Yeo and Josh Hill rotating through there for most of the game. Collins can't cover any of those, so he would have had to go to the pine.
I reckon Collins could be useful in a well-balanced backline. We just don't have one at the moment.