Tony Finau took his second PGA Tour title with a play-off win over Cameron Smith at The Northern Trust, while Shane Lowry finished best of the Irish in a tie for 11th, eight shots off the eventual winner.
The final round of the tournament in New Jersey was pushed into Monday after Hurricane Henri headed towards the north-eastern US coast and the result was delayed as Finau and Smith both finished on 20-under.
Australian Smith twice made back-to-back birdies on the back nine to recover after a double bogey on the fifth to card a four-under 67, while Finau went birdie-eagle-birdie on holes 12-14 to help himself to a six-under 65 to grab a share of the lead after 72 holes.
Smith's tee shot on the first playoff hole - the 18th - landed out of bounds, and Finau carded a par four to take the title.
Seamus Power finished on eight under in a tie for 31st, one shot ahead of Rory McIlroy.
Overnight leader Jon Rahm shot a 69 to finish third, while Alex Noren, Tom Hoge and Justin Thomas were tied for fourth on 15 under.
Lowry finished his tournament on 12 under after a final-day 72 as he teed off in a group alongside eventual winner Finau as well as Thomas.
The Offaly man's final round featured four birdies, but he also dropped shots with a double bogey on 10 and three further bogeys in a one-over round.
Power carded five birdies and three bogeys in a 69, while McIlroy's 70 saw him start off strongly with four birdies on 11, 13, 14 and 16 before he double-bogeyed the first and slipped back into a tie for 43rd after a bogey on the eighth.
Waterford native Power, who claimed his first PGA Tour win with victory at the Barbasol Championship in July which yields the benefits of a a full exemption through to the 2022-23 season and a spot at the Sentry Tournament of Champions, the Players Championship and the PGA Championship, relished the opportunity to be involved in an elite field.
He said: "It was my second time in the Playoffs, and really the first time with a chance to advance to the penultimate one. So it was different for me. These are the fields you want to be playing in. I wish I had my best game coming in here, to give yourself a chance, but I was able to hang in there. Solid week, nothing special, but something to build on for next season."