"We felt that last quarter was where we needed to accelerate and the boys did that," arch-pragmatist Borthwick said after the 34-12 victory that left England exactly where they wanted to be after two games - top of Pool B with two wins against their strongest rivals.
He said the slippery conditions and Japan's aggressive defence had contributed to his side's lack of ambition with ball in hand but his players took that caution to the extreme during a mind-achingly dull first hour.
Again and again England chose to kick when in possession, regardless of how many under-employed backs lined up in desperate hope, rather than any sort of expectation, that they might get the ball.
The tone was set in the first minute when winger Elliot Daly (30), with two men outside him and the Japanese defence scrambling, plopped a kick that ran into the opposition in-goal area.
In what was to become a typical piece of England action, that the idea seemed stilted and the execution poor. Japan, in contrast, ran the ball with gusto and though, to somewhat support Borthwick's theory, they dropped it a lot, they still forced England to defend for their lives.
England were marginally on top as they led 13-12 but continued to kick the ball away almost as soon as they got hold of it and when scrum half Alex Mitchell (26) sent yet another hopeful punt rolling dead early in the second half, frustration among their own fans could not be contained and boos rumbled round the Stade de Nice.
Only Courtney Lawes' (34) fortunate try via the head of prop Joe Marler (33) pulled them clear in the 56th minute but that did nothing to change the approach.
England were playing as if in some structured training session where the law of the day is that any time two passes in a row are made, the whole team drops for 10 press ups.
It was terrible to watch, seemingly more so coming so soon after Fiji had shown the joyous side of rugby with their all-action display against Australia.
Only in the final 10 minutes, with Japan tiring and the fresh impetus of Marcus Smith (24) off the bench, did England start doing what other sides seem to do as routine - slip passes to team mates running hard lines, recycle quickly and repeat.
It brought further tries for Freddie Steward (22) and Joe Marchant (27), a four-try bonus point and the opportunity to "gloss the dross" of what had gone before, not that English pundits were to be seduced.
The Guardian's Jonathan Liew bemoaned England’s "incurable foot fetish" and described watching them on Sunday as "soul-numbing drudgery."
Former England fly half Stuart Barnes compared their constricted game plan with that of defending champions South Africa as they crushed an albeit poor Romania 76-0 with 12 tries earlier in the day, saying in The Times: "The gap between England and the elite is enormous and growing."
Borthwick, of course, will not care a jot. With expected victories over Chile and Samoa and a very winnable quarter-final against Australia, Wales or Fiji to come, he could well be preparing for a semi-final next month which several of those "elite" teams will be watching jealously at home on TV.
