Ok, so by your theory, Hawthorn destabilized Sydney, who finished minor premiers and played in the GF, by going after Tom Mitchell. Would I be correct in saying that as they where stuck into him for 18 months also?
Firstly it is not my theory. You drew a correlation between Betts and Thomas suggesting if one was destabilised, then so was the other. I merely gave you a reason why Thomas wasn't destabilised.
However we can add to this somewhat.
Betts had an average year in 2013. He was well down on his previous form. Was he destabilised? Possibly.
Mitchell was one of the best on ground in the GF. He fought out his year. I question whether Hawthorn had been in to him that long in any meaningful way. Carlton had been linked to him more than any team for 3 years.
Chris Yarran, approached mid season. Did not try at all for most of the rest of the season. Sure, he had some issues going on but clearly checked out.
Lachie Henderson, same thing. Checked out and asked for a trade before the season ended.
Jarrad Waite, played terribly and then got an offer and he played some of his best football to end his time with us. Not destabilised but reinvigorated.
This is what I consider destabilising. Intended or not, there is no doubt some are destablised by early approaches.