I'll throw out a guess why the Kings will believe that until they're forced not to; the 17-18 Washington Capitals. Whether or not they beat TB at this point, or come close against Winnipeg, isn't the point. They are where they are right now. Go read Tampa fans. They're ready to jump.
The Caps traded Johansson for picks(which haven't helped them yet) because of the cap, not value. They gave 30+ Oshie a bad contract. They have bottom of the barrel free agents like Chiasson and Smith-Pelley actually helping them. They lost Schmidt for nothing, and replaced him with a 7th round pick from 6 years ago, and/or Michal Kempny. Orpik is still in their top 5. They have a 29 year old player that had 1 goal in his previous 25 playoff games with 5 in 14 games this year. This was all after their championship window closed, but they've managed to find themselves in a better physical position to win after that window shut than when it was predicted to be open.
That's what the Kings will sell people on.