Rory McIlroy is on the verge of turning consistency into a stream of silverware, according to European Ryder Cup captain Thomas Bjorn.

And the man himself agrees with that bold assessment, even if his attempt to be an "eternal optimist" is being put to the test by seeing chances for high-profile victories slip through his fingers.

McIlroy won the Arnold Palmer Invitational in brilliant style earlier this season, carding a final round of 64 at Bay Hill to win by three shots and claim his first victory since the week before the 2016 Ryder Cup.

But the 29-year-old has also struggled to convert several other opportunities, most notably when chasing the career grand slam in the Masters and failing to convert a three-shot halfway lead in the BMW PGA Championship at Wentworth.

McIlroy also enjoyed a share of the lead late in the final round of the Open at Carnoustie before settling for a tie for second and struggled to a closing 73 in the WGC-Bridgestone Invitational in Akron on Sunday.

"I think he's in a place where he's contending every week and as a player you go through spells where you don't quite get over the line," Bjorn said ahead of the US PGA Championship at Bellerive Country Club.

"He's in a place where it's going to go 'boom' and then he's going to start winning a lot of golf tournaments again, and that's actually pretty good fun to watch."

"He's going through that spell that all players go through at some stage where he's not quite winning them but is still contending.  

"And then eventually when he wins that one, then I think he'll just start rolling again. As a golfer and a guy that's played golf since I was 3 years old, I'll pay money to go and watch him."