Joaquin Niemann … Given his run of success as an amateur that propelled him to No. 1 in the World Amateur Golf Ranking to a litany of leaderboard appearances that yielded a spot on the ballot for the 2017-18 Arnold Palmer Award as a non-member – even though he didn't turn professional until halfway into the season – it might seem like cheating to plug him into this grouping for the Memorial Tournament presented by Nationwide. To further support that narrative, en route to a T6 in his debut last year, he co-led at the midpoint and sat one shot off the lead entering the final round. However, while he's returned to Muirfield Village via a sponsor exemption, the 20-year-old doesn't check the all-important box of recent form. Consider that he's 153rd in the FedExCup with only one top-30 finish in 18 starts this season. The learning curve never loses.
Emiliano Grillo … Still in pursuit of his second PGA TOUR title, it wouldn't surprise anyone if it occurred at Muirfield Village. Despite ups and downs with his putting over the years, he's always had the pace on these greens en route to a 3-for-3 record highlighted by a T11 in 2016. His scoring average in 12 rounds is 70.42. The rest of his game is ready. Thus far this season, the 26-year-old is T7 in total driving, 16th in greens in regulation, T25 in proximity to the hole and 20th in strokes gained: tee-to-green. He's also T38 in par-5 scoring.
Adam Hadwin … At just 5'8" and 165 pounds, the Canuck doesn't profile as a threat for the big ballpark of Muirfield Village, but ignore him at your own risk. He's one of the more accurate from tee to green, including a ranking of T32 in proximity to the hole. And before you think that he's outmanned on par 5s, he's T12 on TOUR in scoring average on those holes of which there are four this week. Granted, he's slipped in recent months, but he's 3-for-4 at Memorial. That includes a T11 in 2016 when he started the final round inside the top five.
Sam Burns … His appearance at last year's Memorial (solo 81st) ended a barnstorming tour through the non-majors as a non-member. Because he exceeded seven starts in 2017-18 (topping out at 11), he was eliminated from contention for the Arnold Palmer Award as a first-time PGA TOUR member this season, and it's been a constructive campaign for the 22-year-old. He's cashed in 13 of 21 starts, five of which for a top 25. He enters this week comfortably safe at 78th in the FedExCup. As he works on improving his irons, he's more than equipped off the tee (28th in distance of all drives) and on the greens (24th in strokes gained: putting and 17th inside 10 feet). Slotting T38 in par-5 scoring won't hurt with a full set of par 5s awaiting his return trip to Muirfield Village.
Justin Suh … It's almost summertime. That means that we're going to be treated regularly to fresh faces from the collegiate ranks. The 21-year-old just wrapped his career at the University of Southern California with a T4 at the NCAA Men's Championship. All told, he captured eight victories as a Trojan and spent time atop the World Golf Amateur Ranking where he's currently No. 2. He's one of the five finalists for the Jack Nicklaus Award, which will be presented on Thursday at Muirfield Village Golf Club where he's making his pro debut. He's also one of the 10 finalists for the Haskins Award won last year by Norman Xiong, who joins him in this week's field.
NOTE: Sleeper is a relative term, so Rob uses unofficial criteria to determine who qualifies. Each of the following usually is determined to be ineligible for this weekly staple: Winners of the tournament on the current host course; winners in the same season; recent major champions; top 50 in the Official World Golf Ranking; recent participants of team competitions.