Rory McIlroy acknowledged there is still plenty of room for improvement in his game after finishing off his work at the US PGA Championship with a final round of 72.

The world number seven came into the tournament with many fancying him to challenge, victory at the Wells Fargo Championship earlier in May suggesting he was returning to form at just the right time.

However, an opening 75 left him with work to do and he was never able to get into contention at Kiawah Island. A bogey at the 18th hole on Sunday saw him end on five over par, meaning the wait for a fifth major goes on.

For McIlroy, the key focus moving forward is finding greater consistency with his driver, having felt it has not been right "for a long time".

Asked to sum up his play on Sunday, he replied: "More of the same, very average.

"I couldn't really get anything going and it was a day where you had to get off to a fast start. The first few holes were playing a lot easier than they have done and I didn't do that, just sort of got stuck in neutral.

"I still have a way to go with everything. I just need to figure out a driver, as well. I just haven't driven the ball as well as I know that I can for a long time, and that's really the foundation of my game."

McIlroy won the US PGA Championship at the same venue in 2012, leading plenty to tip him to produce a repeat result nine years later, particularly coming after his recent success at Quail Hollow.

The man himself, however, was baffled at his status as favourite prior to the tournament, with his game "exposed" by the tricky conditions at the Ocean Course.

"I didn't understand those high expectations," he said. "It was good to win at Quail Hollow, a course that I've always played well on and am comfortable on.

"I didn't feel like playing well here nine years ago was going to automatically make me play well again, and I felt like coming in here there was still parts of my game that I needed to sharpen up, and obviously those parts were exposed this week in the wind and on a tough course."