The Phoenix Suns have not given a long term contract for their head coaching job to an experienced head coach from another team since Alvin Gentry took the full time job in 2009. Coincidentally, Alvin Gentry was the last coach to lead the Suns to the playoffs, in the 2009-2010 season.
If you only count coaches the Suns have hired who were head coaches for another NBA team in the prior season, you have to go back 45 years.
Forty. Five. Years.
Yes, it’s been since 1973 when the Suns hired Butch van Breda Koff (who only coached the team for 7 games).