Pietersen could not find his customary rhythm and departed for six
Stand-in skipper Kevin Pietersen slammed England's batting as his first game in charge ended in a 51-run defeat and a 3-1 series loss to New Zealand.
"We've got ourselves in a position to win matches with our bowlers but our batting has let us down," he said.
"Consistency is the word we're after. You cannot play exceptional cricket and then not play well for two weeks.
"You can't afford to get 20s, 30s, 40s, they don't win series, hundreds do and that's where we let ourselves down."
Since his superb unbeaten century helped England win the first match of the series at Durham, Pietersen has made only 23 runs in the remaining four matches.
"I haven't batted well in the last couple of weeks, we always strive to get better but it just didn't happen," he said. "There have not been enough hundreds. When we beat that great Indian side last year we got three hundreds."
Regarding his team's chase for 267, he added: "We got a pretty decent start but we keep losing wickets."
England coach Peter Moores was also under no illusions that improvements had to be made with the prospect of even stronger opponents in South Africa to follow this summer.
"We've got to find answers," he said. "We can't ignore it. We built a good foundation at Durham but now we've got to go away and work hard as we'll have a tough series against the South Africans."
England conceded 96 from the final 10 overs then slipped from 53-0 to 215 all out and Moores conceded: "We haven't bowled very well at the end of the innings and batting-wise it wasn't good enough.
"We've had some highs but New Zealand they have beaten us twice in two series and we've got to go away and think about that and make sure we work hard."