The Suns' defense showed up in Game 5 - a 110-80 home victory against the Mavericks this past Tuesday. I don't see Phoenix's defense going away in this Game 6 with the series shifting back to Dallas.
The spread is short because the Mavericks defeated the Suns in Games 3 and 4 in Dallas. But the Suns' defense is back to their elite level and Devin Booker is hot, averaging nearly 27 points in the series while making 16 of 32 shots from beyond the arc.
Luka Doncic is the only Dallas player who can be relied upon. Doncic, though, is not getting enough help. The Suns are holding a huge front-court edge and have the stronger bench.
Phoenix is the superior team. It's not asking too much of the Suns to just win this game - after a 30-point crushing victory in the game - before so they can move on to the Western Conference finals.