Gayle struck 23 goals in 32 games to help Newcastle gain promotion in 2016-17 but struggled for such form once back in the Premier League.
Expected to be in and around the relegation places, Benitez galvanised his squad as they finished 10th, a massive 11 points off the bottom three.
However, further investment is needed this summer to ensure that they can sustain their place in the Premier League.
USA job growth slows in July, unemployment rate dips
The U.S. central bank said "the labor market has continued to strengthen and economic activity has been rising at a strong rate". Mortgage rates have also increased in the past year, lifting monthly payments and making many homes even less affordable.
And after Newcastle's 4-0 friendly defeat to Braga in midweek, Benitez delivered a blunt transfer update which left many supporters anxious over his long-term future at the club.
Benitez is particularly frustrated at Newcastle's failure to meet Rondón's £16.5mn release clause but the striker is almost 29 and Ashley does not like signing players over 26 because he feels they become depreciating assets. We were poor and we made too many mistakes.
"Things are not going well off the pitch and you can see a reflection of that on the pitch", he said.
Following a victory over Chelsea on the last day of the season last campaign, supporters were in ecstasy. "We were following him for quite a while", Benitez said.
Centre of defence sees only Ciaran Clark (303 minutes) get significant time on the pitch, with Jamaal Lascelles (180 minutes) next best, but Lejeune now injured and summer signing Fabian Schar only 102 minutes.