Only four of the 54 players in action shot higher than McIlroy’s 74 as his bid for a career Grand Slam crashed and burned.
A share of fifth place, six shots behind winner Patrick Reed, was a bitter disappointment but he promises he will be back.
“I played probably some of the best golf I’ve ever played here; it just wasn’t meant to be. Of course it’s frustrating and it’s hard to take any positives from it right now but at least I put myself in a position – that’s all I’ve wanted to do,” he said.
“For the last four years I’ve had top tens but I haven’t been close enough to the lead. Today I got myself there, I didn’t quite do enough but I’ll still come back next year and try again.
“I think 100 per cent I can come back and win here. I play this golf course well. I just haven’t played it well enough at the right times.”
McIlroy’s missed tiddler for an eagle at the second hole which would have tied for him for the lead appeared to be a turning point but he pointed to the bogeys at the third and fifth as more important in allowing Reed to keep his nose in front.
“I’d say three and five are the ones that I’d look back on thinking if I could have made pars there it could have been a different story,” he said.
“Every time I took a step forward I took a step back on the next hole. I had a chance to maybe put a bit more pressure on him than I did.
“I’ll sit down and reflect over the next few days and see what I could have done better. Whether it be mindset or whatever, I just didn’t quite have it today.
“The putter let me down a little bit, I just wasn’t quite as trusting as I was the first few days and that made a big difference. When I did get some chances I didn’t take advantage of them.
“I feel like momentum is a huge thing, especially in final rounds. You look at what Jordan [Spieth] and Rickie [Fowler] did – they got on a roll and I just didn’t. It wasn’t as if nerves got to me. I just didn’t quite have it.
“It was a tough day and hopefully I’ll be better next time.”
