The Dell Technologies Championship was Justin Thomas' to lose on Sunday evening. He started Round 4 on Monday tied with Marc Leishman at 12 under, having Jordan Spieth, Dustin Johnson and others in hot pursuit. After Leishman and Spieth played the front nine in a combined 60 on Monday, Thomas looked like he was going to be left in their wake, even after shooting a 32 of his own. But those two cooled off, and Thomas shut things down with a strong 34 on the back nine to clear Spieth by three for his fifth PGA Tour win of the season.

Thomas got it done this week with every club except the one in his bag that is most lethal -- his driver. Thomas was outside the top 15 in strokes gained with the driver at TPC Boston, but made up for it with his putting, where he finished inside the top five. He also only made two bogeys in 72 holes en route to the victory.

The dagger on Monday, if there was one, came on the 15th hole when he stuck his approach from 137 yards and made birdie to go two clear of Spieth. He saved par on No. 16, parred the last two and held a trophy for the fifth time on the season.

It also helped that Spieth and Leishman faded after electric starts. Spieth stumbled to a 37 on the back with a bogey at the last, and Leishman unfurled an ugly 40. Thomas cruised just as he's done all season.

"Patience," Thomas told NBC's Steve Sands about what he's learned about how to win. "(Caddie) Jimmie (Johnson) does such a good job keeping me patient. We stay within every shot. Whatever happens, we don't worry about what other guys are doing and what I just did. All we're trying to do is just hit the next shot the best that we can. He's helped me so much. We've had a great year, obviously there are two more events to try and finish it off."

The win for Thomas is bigger than just his fifth on the season. He's No. 2 in the FedEx Cup and likely sealed the PGA Tour Player of the Year race with this victory. He'll have a chance at the Tour Championship to get win No. 6 (or 7?) and touch off one of the great seasons in recent memory for anyone (much less for somebody who's not even 25 yet).

On Monday, he joined an historic club that includes Spieth, Jack Nicklaus and Tiger Woods. Players under age 25 who have won five or more times in a season including a major championship.

Woods ruined us, of course, when it comes to expectations, and Spieth sort of ruined what Thomas has done this year. Because Spieth won two majors in 2015 on his way to that preposterously good year, we think that's the standard. It's not. It's an outlier. What Thomas is doing this season is as good as anything we've seen in a long, long time, and what he did this week at TPC Boston -- 17 birdies, an eagle and just two bogeys -- was one of his better performances of the year. 

With two playoff events still to play, Thomas has left an indelible print on the 2016-17 season and has just one more mountain left to climb. Oh, and there is $10 million at the top of it.

Here are the rest of our grades for the Dell Technologies Championship

Jordan Spieth (2nd): Two straight playoff events, two straight runner-up finishes for Spieth. You know what that means, right? Spieth is going to burn down the last two events and take home the $10 million FedEx Cup prize. I'll regret saying this, but he's the most consistently great player we've seen on the PGA Tour since Tiger Woods was thriving in his prime. That doesn't mean he's as good as Woods was, or even close, but from a consistency standpoint, there's nobody as good as Spieth right now. Also, I would listen to Spieth mic'd up talking about what I'm eating for breakfast. Grade: A

Jon Rahm (T4): I thought we'd see more in the final two rounds after Rahm led at the midway point. He didn't play poorly in Rounds 3 and 4, but a 3-under total just wasn't getting it done this week. Still, after a bumpy stretch this summer, Rahm appears to be fully back on track. He'll likely be in the top five heading to the Tour Championship, which means he'll control his own destiny when it comes to the $10 million FedEx Cup grand prize. Grade: A-

Phil Mickelson (T6): After discovering and treating a mysterious illness, Mickelson had one of his best finishes of the season. Of course, Mickelson is not here for top-10 finishes. He wants to win, but he doesn't seem to have that sixth gear that Justin Thomas or Jordan Spieth have right now. That doesn't mean he'll never win again on the PGA Tour, but it will take a herculean effort from him to do so. The good news is that he's likely played himself into a spot on the Presidents Cup team with his showing this week. He was probably going to make it anyway, but this week sealed the deal. Grade: A (F for the shank)

Bubba Watson (T69): Watson needed a big finish this week to make it to the BMW Championship, and he didn't get it. Watson finished outside the top 70, and he's probably the biggest name to not move on to the penultimate FedEx Cup Playoff event. It was a strange year for Watson, who only had four top 10s. His best finish was a top five at the team event at the Zurich Classic, and he missed the cut at three of the four majors. Watson insisted recently that he still craves greatness, but now he has something to prove in 2018 after an off year for him. Grade: D