England's repeated humiliation was completed at Headingley where Sri Lanka, despite being set 322 for victory, romped home by eight wickets with more than 12 overs to spare after a dominating 99-ball 152 from Sanath Jayasuriya in a world-record opening stand of 286 with Upul Tharanga (109).
The defeat was England's worst in a head-to-head One-day series although they did lose all six limited overs Internationals against Australia and Pakistan in the 2001 home triangular event.
It had seemed they were belatedly about to give Sri Lanka a game when, after Strauss won the toss, Trescothick scored 121.
It was England's first individual One-day hundred against a major nation since the Somerset left-hander himself reached three figures against Australia at Headingley nearly a year ago.
But Strauss's effort was put into context by Jayasuriya's innings, an ideal way for the 37-year-old veteran to join India's Sachin Tendulkar and Pakistan's Inzamam-ul-Haq with a world-record 362 One-day International appearances.
"I don't remember anyone batting like that against us to that extent and for so long," said Trescothick of the reverse that can have done little for morale in the run-up to next year's World Cup in the Caribbean.
"The odd person can get 70 or 80 maybe, but to get 150 off 99 balls is just destructive. The game is taken away from you before you even have chance to get into it."
Strauss tried several unusual tactics to staunch the flow of runs, although delaying the entrance of strike bowler Stephen Harmison until second change, for example, did not help England's cause.
But Trescothick said Strauss, the leading candidate to captain the team in the absence of the injured Michael Vaughan in the upcoming Test series against Pakistan, which starts at Lord's on July 13, should not have his leadership credentials demolished on the basis of a one-day series where England's injury-hit attack frequently struggled to bowl straight.
"I do think he's done a decent job. It's a really tough situation that he is in," said Trescothick, who himself filled in for Vaughan when the Ashes-winning captain had trouble with his knee in Pakistan late last year.
"When things are not going right and everything you try goes wrong it is easy for people to criticise.
"But I think the thing is to just give Andrew a fair crack of the whip, and then we'll have a better idea of how good a captain he is."
Of his own innings, Trescothick said: "It is, of course, very nice to get a hundred. But in the context of the game it is totally irrelevant at the end of the day.
"Anywhere above 300 you feel as if you've got a very good chance if you bowl and field well.
"We didn't quite get it in the zones we wanted to, but when you come up against someone like Sanath Jayasuriya in that sort of form it can be quite tough."
Sri Lanka captain Mahela Jayawardene, whose youthful side came from behind to square the preceding Test series 1-1, was keen not to have the efforts of his team diminished by England's problems.
"To finish the series on such a high note has been brilliant," he said. "There was a little bit of old Sanath there today, and it is very difficult to stop him when he is in that kind of mood.
"When I walked out to bat I could tell England were pretty down and out. The way Sanath played today any decent attack would have gotten the same from him.
"I've seen him going against Australia, with Glenn McGrath, Brett Lee and Jason Gillespie and he has done the same thing."