My goodness, the Mavs are certainly going all-in. I'll be curious to see if Kristaps Porzingis remains a special talent when he returns to the court. When he was drafted, the idea of a "unicorn" big man was still novel. Now, starting 4's and 5's all across the league are expected to possess a wide range of skills. Does he pick up where he left off, and does he elevate this Mavericks team into the playoff picture next season? If healthy, I would say "yes." Of course, Porzingis has yet to play a full NBA season, and his injury history is not exactly encouraging. But he's also certainly a better return on Dennis Smith Jr. then I ever expected the Mavs to get. The move is not without risk, but they also would have been crazy not to pull the trigger.
However, I am rather surprised that New York traded Porzingis for so little. DSJ and expirings? Really? Are they that optimistic about their chances in free agency, given how bare their roster is at present? New York has fallen flat on their face with that strategy time and again in the last decade, and I would not be very thrilled if I were a Knicks fans right now...
edit: Ah, I see now that Dallas is also giving up two future first round picks to the Knicks in the deal. I suppose that justifies it a bit more from New York's perspective. And it also means that Dallas is seriously all-in. Damn, they had better make waves in free agency to bring in quality talent to build around Doncic/Porzingis, because there's not much left for the Mavs to work with.