Although that only ranked 26th, he was particularly effective on Sunday, posting a 1.717 strokes-gained mark, including crucial two-putts on 16 and 17 (the former for birdie to bring his cushion to two strokes) before knocking in a three-footer for birdie at the last for the clincher.
Brendan Steele shot a three-under round of 69 to clinch the Safeway Open trophy for the second year in a row.
Zac Blair (66) and Tony Finau (65) were 9 under, and Graham DeLaet (67) and Brian Davis (66) were another stroke back.
However, his surprising display at the par-5 16th at the Silverado Resort and Spa's North Course, provided a hilarious moment for those watching.
World number 29 Phil Mickelson may not have been in the best form over the last few years but that has not deterred him from seeing the amusing side of his wayward hitting.
Mickelson, playing in his 91st PGA Tour event since his last win, finished eighth in the tournament a year ago and has six straight rounds in the 60s at Silverado.
The American had a favourable bounce on the approach to the par-five fifth and holed the subsequent putt to eagle the hole in a round which included six birdies, and is now clear 7/1 favourite with Sky Bet. That was a strong 3-under 69 on Sunday, but that double bogey may haunt him for a bit.
"But my dad does a great job of reminding me I've done a lot of great things", Thomas said, "and I will continue to do a lot of great things if I continue to work hard and continue to do the right things". I had a really good ball-striking day.
"I'm getting pretty spoiled winning the first event of the year twice", said Steele, the 34-year-old from the Southern California mountain town of Idyllwild. Errant driving throughout the week perhaps cost the Hall of Famer his 43 PGA Tour victory.
Fresh off a dominant Presidents Cup victory, Phil Mickelson got the 2017-18 PGA Tour season kicked off with a t-3 with Chesson Hadley at 12 under.
I played really well the whole day, said Hoge, whose PGA Tour career best is a tie for fourth in August at the Barracuda Open.
He added an eagle on the fifth but followed with a bogey on the next hole.
2 - Phil Mickelson continued his good run of form with a tied third finish at Silverado. Mickelson hasn't won on the PGA Tour since the 2013 Open Championship.
After a bogey on the second hole, Mickelson birdied five of his last six holes on the front nine to move to 11 under and within two shots of the lead.
Sangmoon Bae carded a one-over 73 on his return to the PGA Tour after serving military service in his native South Korea, dropping four shots in a row but scoring birdies on the 12th and 18th.