These days it seems like there are only ever a few teams in the position to court the really high profile UFAs, though. It always seems to come down to only a few teams anyway that have the requisite: cap space, contention window, roster composition, and meet whatever random personal preferences a player might have. So I dunno, but SJ nabbing Karlsson seems to me like they would really be acquiring at least a legit chance at re-signing him long term and convincing him to stay.
I mean, they'll have Thornton retiring in all likelihood, and I don't know if Pavelski even as good as he is gets much of a raise at his age. So SJ seems to have a lot of the boxes checked for being able to court Karlsson in the first place, and getting him there now should be worth something significant to them.
I still feel like they underpaid therefore... it wasn't quite like obtaining a total rental version of Karlsson. They also got themselves an inside track relative to what is probably a very short list of potential destinations for him anyway.