Westwood and fellow former world number one Martin Kaymer were given wild cards by Clarke as the Tyrone man looked for experience to balance the six rookies in his team at Hazeltine.
However, while Clarke’s final choice, Thomas Pieters, justified his selection by winning four points from five matches, Westwood lost all three and Kaymer’s only win from four games came in Sunday’s singles.
Asked if he felt he had let down his good friend Clarke, Westwood said: “Yeah, a little bit. I was a captain’s pick and I would have liked to have performed well for him, but we sat down (afterwards) and chatted about it.
“He said: ‘What could I have done differently?’ and I said: ‘I thought you did all you could’. The American team did to us what we have been doing to them the last 20 years.
“A lot of people said to me it’s a good result for the Ryder Cup and it keeps the interest in it. We had won it three times in a row. Sooner or later they are going to win one and it just happened to be under Darren’s watch.
“It’s unfortunate and there’s not a lot you can do , really. They had a strong team and I thought they got the set-up spot on for their team, when you look at it.”
Westwood took responsibility for his foursomes loss with Pieters and told Clarke he should be left out of the afternoon session, preferring to work on his game with coach Pete Cowen. And although he feels that work paid off with better play in Saturday’s fourballs, he and Masters champion Danny Willett still lost to Ryan Holmes and JB Moore on the 18th.
Both European players bogeyed the par-three 17th to trail for the first time, before Westwood missed from two feet for a birdie on the 18th to salvage half a point.
The 43-year-old insists he has not lost sleep over that moment, adding: “I rarely lose sleep and people are always going to miss putts. It was a lot of pressure on that situation and just one of those things. I didn’t put a good stroke on it and shoved it a bit and didn’t go in. I think sometimes I get judged unfairly on my putting because the rest is so strong.”
Westwood looked set to claim at least one point from the week - he needs two and a half to overtake Nick Faldo as Europe’s all-time record points scorer - when he moved two up with three to play against Moore in the singles.
But Moore then eagled the 16th and birdied the 17th before Westwood bogeyed the last. “It’s just symptomatic of the way the week went really,”