Spitty C raised some points on the all together podcast. That Benitez does well at clubs on the so called "fringes of the elite". Which included the likes of Valencia, Liverpool (at the time), and Napoli. So after looking into that:
VALENCIA
Three seasons pre-Benitez
Average League position: 4th
Notable Trophies: Copa Del Rey, Intertoto Cup, Supercopa,
Three seasons of Benitez
Average League position: 2nd
Notable Trophies: La Liga x2, UEFA Cup
Three seasons post Benitez:
Average League position: 5th
Notable Trophies: N/A
LIVERPOOL
Six seasons pre-Benitez
Average League position: 4th
Notable Trophies: (UEFA Cup, UEFA Super Cup, FA Cup, League Cup x2)
Six seasons of Benitez
Average League position: 4th
Notable Trophies: UEFA Champions League, UEFA Super Cup, FA Cup)
Six seasons post Benitez
Average League position: 6th
Notable trophies: League Cup
NAPOLI:
Two seasons pre-Benitez:
Average League position: 3
Notable Trophies: Coppa Italia
Two seasons of Benitez
Average League position: 4
Notable Trophies: Coppa Italia, Supercopa Italia
Two seasons post Benitez
Average League position: 2
Notable Trophies: N/A
Average goals scored / Conceded in league
VALENCIA
1999-2001: 59 / 37
2001-2004: 59 / 29 (Benitez era)
2004-2007: 56 / 38
LIVERPOOL
1999-2004: 62 / 37
2004-2010: 62 / 30 (Benitez era)
2010-2016: 65 / 49
NAPOLI
2011-12 - 69 / 41
2013-15 - 73 / 46 (Benitez era)
2015-17 - 87 / 35