Javier Hernandez, a £16m-signing in 2017, with two goals and a late strike from £36m summer capture Felipe Anderson ended the Magpies’ run of three successive wins. The visiting attack also included Marko Arnautovic, who cost the London club £20m last season.
In contrast to the Hammers, who spent close to £100m in the last transfer window, Newcastle made a net profit of £20m from their transactions.
Benitez said: “They have spent the money on offensive players and they made the difference.
“We are working on [signings in January], but it is a question of money. What they spend, what we spend, you can see that on the pitch.
“I cannot complain of the effort of the players or the commitment but again today we had chances, but they scored theirs.”
Hernandez grabbed his first in the 11th minute, just as some Newcastle fans were taking to their seats following a “walk-in protest” against the club owner – had they waited another minute they would not have witnessed the calamitous defending from their side.
Robert Snodgrass was allowed to run down the left and deliver an in-swinging cross for his Mexican team-mate who got himself in front of Federico Fernandez to poke in.
Hernandez then missed a couple of great chances before he fired home the second from Arnautovic’s flick-on.
And with the final kick of the game, Anderson capped off an exceptional display by slotting in West Ham’s third under the body of keeper Martin Dubravka.
The victory was only the Hammers’ second in the league at Newcastle since 1998, and moves them into 13th spot, on 15 points, Newcastle drop down to 14th and have 12 points.
West Ham’s heavy home defeat by Manchester City last week was an anomaly because of the stature of their opponents. At St James’ Park, the Hammers found themselves against a team with similar aspirations for the season and on the same number of points – however, by full-time it was quite stark that there was a difference in quality between the two sides.
A large chunk of West Ham’s summer transfer budget went on midfielder Anderson who produced a man-of-the-match performance that showcased his surging runs and great range of passing.
He deservedly got on the scoresheet with seconds remaining when he brushed off a weak challenge from Fabian Schar to slot home. The Brazilian had also provided a brilliant ball for Hernandez, who should have hit the target instead of the side-netting with the score at 1-0.
The Mexican got the ball rolling with a close-range finish in the first-half, and finally scored his second on 63 minutes when he latched on to Arnautovic’s header and fired low past Newcastle’s Czech keeper.
