Sri Lanka, who battled back to draw the Test series with England 1-1, maintained their good form against the hosts by winning Thursday's Twenty20 clash by two runs and followed that up with a convincing 20-run victory at Lord's on Saturday in the opening encounter of a five-match One-day series.
"We got off to a good start at Lord's," Moody told reporters at The Oval here Monday after seeing his side confidently defend a total of 257 last weekend.
"It was pleasing. But I felt we should have got 300, and I also felt we can field better than that."
Sri Lanka's win was helped by England's One-day record 42 extras, which included 23 wides.
"In One-day cricket, you don't want to be bowling wides and no-balls, it's quite clear. It's a discipline we're quite strong with our guys," added former Australia international Moody, whose team bowled just three wides.
"England won the toss and they were eager to make early inroads on a wicket that appeared to have little bit of life in it. There's no doubting the quality of their attack, they had a bad day at the office."
And England coach Duncan Fletcher said of his bowlers: "At the end of the day they don't mean to bowl wides."
Meanwhile Moody, formerly coach of English county Worcestershire, said he was pleased with the progress made by his largely youthful side as evidenced by 21-year-old opener Upul Tharanga's man-of-the-match winning hundred at Lord's.
"If we win this One-day series, and we've got a long way to go, we'll fly out of England a satisfied team. It's important to have the young players playing on a regular basis. In the short to mid-term we'll continue to see the benefits like we saw with Upul Tharanga at Lord's."
England lost a One-day series 5-1 in India earlier this year and Saturday's defeat further dampened hopes of success at next year's World Cup in the Caribbean.
"It seems like there's a huge turnover in the one-day squad," Moody, a World Cup-winner as a player with Australia in 1999, said. "Sometimes it's hard for a player to establish themselves in any position in the one-day side."
And he said Worcestershire batsman Vikram Solanki, now no longer in England's One-day squad after being shunted up and down the order, would have gained from an extended run in one position.
"I suppose he is an example of a player that probably has been shuffled and would have benefited with patience and the confidence that he's there for a period of time.
"It seems England are still trying to find their magic formula in their top six and the pieces haven't quite yet fallen.
"Injuries haven't helped," added Moody of an England side missing six senior players. "But the last thing we can do as a team is to become complacent."
Both coaches indicated they were unlikely to change their respective teams. "There's a very good chance we'll go in with the same side and they've got to go there and put it right," said Fletcher.