The Leafs acquired Tanev just ahead of the free agency period opening. The Dallas Stars were working hard to extend their trade deadline acquisition, but once it became clear they could not reach an agreement, Jim Nill elected to trade his rights to the Leafs in exchange for a 7th round draft pick.
The move should be a good one for the Leafs, at least in the short-term. Six years is a long contract to hand out to any player, let alone one who is already 34. Based on public models, Tanev is expected to provide the team with great value for the next couple of seasons, but age-related decline will likely see the final years of the deal become troublesome for the team.
Ultimately though, the hockey side of things did not appear to be the driving factor for Tanev choosing Toronto. Rather, he seemed to want to make the best move for his family. For him, that meant going back to Toronto where he grew up, and where his parents still live. Notably, Tanev and his wife are currently expecting their second child. This move means his kids will get to spend more time with their grandparents.
That is certainly one of the more wholesome reasons to sign with a particular team. Hopefully for Tanev, he will get to have his cake and eat it too, as the Leafs look to win their first Stanley Cup in more than 50 years.